[Engine-devel] Domain rescan action question
--_000_CC3DB8AB143Crickyhnetappcom_ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Hey all, As I'm making progress with the domain rescan functionality, I've realized = that I'm unsure what to do with any disks that are detected on the domain. = Should I add them back into the database to be listed as floating disks, or= should I just return a list of disk images to be attached to whatever the = caller of the query needs? - Ricky --_000_CC3DB8AB143Crickyhnetappcom_ Content-Type: text/html; charset="us-ascii" Content-ID: <AFED18B724BEEE4683245253976CBF7B@tahoe.netapp.com> Content-Transfer-Encoding: quoted-printable <html> <head> <meta http-equiv=3D"Content-Type" content=3D"text/html; charset=3Dus-ascii"=
</head> <body style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-lin= e-break: after-white-space; color: rgb(0, 0, 0); font-size: 14px; font-fami= ly: Calibri, sans-serif; "> <div>Hey all,</div> <div><br> </div> <div>As I'm making progress with the domain rescan functionality, I've real= ized that I'm unsure what to do with any disks that are detected on the dom= ain. Should I add them back into the database to be listed as floating disk= s, or should I just return a list of disk images to be attached to whatever the caller of the query needs?</= div> <div><br> </div> <div>- Ricky</div> </body> </html> --_000_CC3DB8AB143Crickyhnetappcom_--
On 07/31/2012 11:30 PM, Hopper, Ricky wrote:
Hey all,
As I'm making progress with the domain rescan functionality, I've realized that I'm unsure what to do with any disks that are detected on the domain. Should I add them back into the database to be listed as floating disks, or should I just return a list of disk images to be attached to whatever the caller of the query needs?
- Ricky
i'm not sure they should be added automatically. I think a dialog[1] showing orphan disks/images on the storage domain for user to choose which to import as 'floating' disks would be better than auto importing them. there is also the reverse of flagging existing disks as 'missing' in storage? [1] or a subtab on the storage domain.
----- Original Message -----
On 07/31/2012 11:30 PM, Hopper, Ricky wrote:
Hey all,
As I'm making progress with the domain rescan functionality, I've realized that I'm unsure what to do with any disks that are detected on the domain. Should I add them back into the database to be listed as floating disks, or should I just return a list of disk images to be attached to whatever the caller of the query needs?
- Ricky
i'm not sure they should be added automatically. I think a dialog[1] showing orphan disks/images on the storage domain for user to choose which to import as 'floating' disks would be better than auto importing them.
why? this same functionality would be used to import an existing domain. If these disks are referenced in OVFs we are not familiar with on this domain then we should import the *VMs*. If they are referenced by other VMs that are already in the system (but disks have been unreachable until now) then the disks should just be added to the db in attached mode. If neither, then the disks should be added as floating disks. For the import functionality, once you subsequently import another domain with OVFs which do reference these disks then if user hasn't appropriated them for other VMs then they would move to attached state, otherwise need to add those VMs with errors. Note that there are 2 reasons for unknown valid disks to be on the domain: 1. delete was initiated in engine but not performed on storage (then floating is fine as only way to automatically delete them is if user chooses to do so) 2. disks were created there outside of the system - should just detect and import and use logic above.
there is also the reverse of flagging existing disks as 'missing' in storage?
If disks were floating then they should just be removed, otherwise should be moved to illegal state (we have this state for disks today).
[1] or a subtab on the storage domain.
Another sub-tab for disks? It's possible but what would you do when importing an existing domain into the system? require user to manually select which disks to import? or would you have different flows for import of domain and rescan of contents? (I'd rather keep it simple with less tabs and manual operations for user to perform, seems more intuitive to me).
On 08/01/2012 12:21 AM, Ayal Baron wrote:
----- Original Message -----
On 07/31/2012 11:30 PM, Hopper, Ricky wrote:
Hey all,
As I'm making progress with the domain rescan functionality, I've realized that I'm unsure what to do with any disks that are detected on the domain. Should I add them back into the database to be listed as floating disks, or should I just return a list of disk images to be attached to whatever the caller of the query needs?
- Ricky
i'm not sure they should be added automatically. I think a dialog[1] showing orphan disks/images on the storage domain for user to choose which to import as 'floating' disks would be better than auto importing them.
why? this same functionality would be used to import an existing domain. If these disks are referenced in OVFs we are not familiar with on this domain then we should import the *VMs*. If they are referenced by other VMs that are already in the system (but disks have been unreachable until now) then the disks should just be added to the db in attached mode. If neither, then the disks should be added as floating disks. For the import functionality, once you subsequently import another domain with OVFs which do reference these disks then if user hasn't appropriated them for other VMs then they would move to attached state, otherwise need to add those VMs with errors.
Note that there are 2 reasons for unknown valid disks to be on the domain: 1. delete was initiated in engine but not performed on storage (then floating is fine as only way to automatically delete them is if user chooses to do so) 2. disks were created there outside of the system - should just detect and import and use logic above.
there is also the reverse of flagging existing disks as 'missing' in storage?
If disks were floating then they should just be removed, otherwise should be moved to illegal state (we have this state for disks today).
[1] or a subtab on the storage domain.
Another sub-tab for disks? It's possible but what would you do when importing an existing domain into the system? require user to manually select which disks to import? or would you have different flows for import of domain and rescan of contents? (I'd rather keep it simple with less tabs and manual operations for user to perform, seems more intuitive to me).
I'm not sure orphaed images and importing an entire domain should be the same flow from UX part. and for a netapp native clone, you'd want to only import the newly cloned ("orphaned) image from the storage via an api call, not the entire domain/images
----- Original Message -----
On 08/01/2012 12:21 AM, Ayal Baron wrote:
----- Original Message -----
On 07/31/2012 11:30 PM, Hopper, Ricky wrote:
Hey all,
As I'm making progress with the domain rescan functionality, I've realized that I'm unsure what to do with any disks that are detected on the domain. Should I add them back into the database to be listed as floating disks, or should I just return a list of disk images to be attached to whatever the caller of the query needs?
- Ricky
i'm not sure they should be added automatically. I think a dialog[1] showing orphan disks/images on the storage domain for user to choose which to import as 'floating' disks would be better than auto importing them.
why? this same functionality would be used to import an existing domain. If these disks are referenced in OVFs we are not familiar with on this domain then we should import the *VMs*. If they are referenced by other VMs that are already in the system (but disks have been unreachable until now) then the disks should just be added to the db in attached mode. If neither, then the disks should be added as floating disks. For the import functionality, once you subsequently import another domain with OVFs which do reference these disks then if user hasn't appropriated them for other VMs then they would move to attached state, otherwise need to add those VMs with errors.
Note that there are 2 reasons for unknown valid disks to be on the domain: 1. delete was initiated in engine but not performed on storage (then floating is fine as only way to automatically delete them is if user chooses to do so) 2. disks were created there outside of the system - should just detect and import and use logic above.
there is also the reverse of flagging existing disks as 'missing' in storage?
If disks were floating then they should just be removed, otherwise should be moved to illegal state (we have this state for disks today).
[1] or a subtab on the storage domain.
Another sub-tab for disks? It's possible but what would you do when importing an existing domain into the system? require user to manually select which disks to import? or would you have different flows for import of domain and rescan of contents? (I'd rather keep it simple with less tabs and manual operations for user to perform, seems more intuitive to me).
I'm not sure orphaed images and importing an entire domain should be the same flow from UX part. and for a netapp native clone, you'd want to only import the newly cloned ("orphaned) image from the storage via an api call, not the entire domain/images
For proper bookkeeping I think we'd want these disks to be reflected in the GUI. I do not however think we need to add additional tabs for this. We could have yet another state ('orphaned' or sth.) for disks to be able to easily differentiate in the GUI etc. I would imagine we'd regularly scan domains to account for storage usage. If we do add such a state then we'd need an API to 'enable' it (so that it could be done automatically).
----- Original Message -----
From: "Itamar Heim" <iheim@redhat.com> To: "Ricky Hopper" <Ricky.Hopper@netapp.com> Cc: engine-devel@ovirt.org Sent: Tuesday, July 31, 2012 4:44:34 PM Subject: Re: [Engine-devel] Domain rescan action question
On 07/31/2012 11:30 PM, Hopper, Ricky wrote:
Hey all,
As I'm making progress with the domain rescan functionality, I've realized that I'm unsure what to do with any disks that are detected on the domain. Should I add them back into the database to be listed as floating disks, or should I just return a list of disk images to be attached to whatever the caller of the query needs?
- Ricky
i'm not sure they should be added automatically. I think a dialog[1] showing orphan disks/images on the storage domain for user to choose which to import as 'floating' disks would be better than auto importing them.
there is also the reverse of flagging existing disks as 'missing' in storage?
Perhaps we should start a feature page to discuss and better scope it. There is a feature page that we could expand, it doesn't discuss the notion of importing those disks which is certainly something we need to address. http://wiki.ovirt.org/wiki/Features/Orphaned_Images
[1] or a subtab on the storage domain.
_______________________________________________ Engine-devel mailing list Engine-devel@ovirt.org http://lists.ovirt.org/mailman/listinfo/engine-devel
----- Original Message -----
From: "Andrew Cathrow" <acathrow@redhat.com> To: "Itamar Heim" <iheim@redhat.com>, "Dan Yasny" <dyasny@redhat.com>, "Ricky Hopper" <Ricky.Hopper@netapp.com> Cc: engine-devel@ovirt.org Sent: Wednesday, August 1, 2012 12:24:42 AM Subject: Re: [Engine-devel] Domain rescan action question
----- Original Message -----
From: "Itamar Heim" <iheim@redhat.com> To: "Ricky Hopper" <Ricky.Hopper@netapp.com> Cc: engine-devel@ovirt.org Sent: Tuesday, July 31, 2012 4:44:34 PM Subject: Re: [Engine-devel] Domain rescan action question
On 07/31/2012 11:30 PM, Hopper, Ricky wrote:
Hey all,
As I'm making progress with the domain rescan functionality, I've realized that I'm unsure what to do with any disks that are detected on the domain. Should I add them back into the database to be listed as floating disks, or should I just return a list of disk images to be attached to whatever the caller of the query needs?
- Ricky
i'm not sure they should be added automatically. I think a dialog[1] showing orphan disks/images on the storage domain for user to choose which to import as 'floating' disks would be better than auto importing them.
there is also the reverse of flagging existing disks as 'missing' in storage?
Perhaps we should start a feature page to discuss and better scope it. There is a feature page that we could expand, it doesn't discuss the notion of importing those disks which is certainly something we need to address.
+1 also, how will be handled images with snapshots? or broken chain of images (not sure its a valid scenario)
[1] or a subtab on the storage domain.
_______________________________________________ Engine-devel mailing list Engine-devel@ovirt.org http://lists.ovirt.org/mailman/listinfo/engine-devel
_______________________________________________ Engine-devel mailing list Engine-devel@ovirt.org http://lists.ovirt.org/mailman/listinfo/engine-devel
----- Original Message -----
From: "Andrew Cathrow" <acathrow@redhat.com> To: "Itamar Heim" <iheim@redhat.com>, "Dan Yasny" <dyasny@redhat.com>, "Ricky Hopper" <Ricky.Hopper@netapp.com> Cc: engine-devel@ovirt.org Sent: Wednesday, 1 August, 2012 12:24:42 AM Subject: Re: [Engine-devel] Domain rescan action question
----- Original Message -----
From: "Itamar Heim" <iheim@redhat.com> To: "Ricky Hopper" <Ricky.Hopper@netapp.com> Cc: engine-devel@ovirt.org Sent: Tuesday, July 31, 2012 4:44:34 PM Subject: Re: [Engine-devel] Domain rescan action question
On 07/31/2012 11:30 PM, Hopper, Ricky wrote:
Hey all,
As I'm making progress with the domain rescan functionality, I've realized that I'm unsure what to do with any disks that are detected on the domain. Should I add them back into the database to be listed as floating disks, or should I just return a list of disk images to be attached to whatever the caller of the query needs?
- Ricky
i'm not sure they should be added automatically. I think a dialog[1] showing orphan disks/images on the storage domain for user to choose which to import as 'floating' disks would be better than auto importing them.
there is also the reverse of flagging existing disks as 'missing' in storage?
Perhaps we should start a feature page to discuss and better scope it. There is a feature page that we could expand, it doesn't discuss the notion of importing those disks which is certainly something we need to address.
The original idea was to scan the storage domains and compare the images lists to the database, thus getting a list of images no longer relevant and scrubbing the storage. This will actually be addressed properly in the future (Ayal can elaborate on that) but for now this is needed at least for that use case. As I understand, the conversation here is about trying to take an already populated SD (from another setup I suppose), scanning it and putting it into RHEV?
[1] or a subtab on the storage domain.
_______________________________________________ Engine-devel mailing list Engine-devel@ovirt.org http://lists.ovirt.org/mailman/listinfo/engine-devel
-- Regards, Dan Yasny Red Hat Israel +972 9769 2280
On 8/1/12 5:59 AM, "Dan Yasny" <dyasny@redhat.com> wrote:
----- Original Message -----
From: "Andrew Cathrow" <acathrow@redhat.com> To: "Itamar Heim" <iheim@redhat.com>, "Dan Yasny" <dyasny@redhat.com>, "Ricky Hopper" <Ricky.Hopper@netapp.com> Cc: engine-devel@ovirt.org Sent: Wednesday, 1 August, 2012 12:24:42 AM Subject: Re: [Engine-devel] Domain rescan action question
----- Original Message -----
From: "Itamar Heim" <iheim@redhat.com> To: "Ricky Hopper" <Ricky.Hopper@netapp.com> Cc: engine-devel@ovirt.org Sent: Tuesday, July 31, 2012 4:44:34 PM Subject: Re: [Engine-devel] Domain rescan action question
On 07/31/2012 11:30 PM, Hopper, Ricky wrote:
Hey all,
As I'm making progress with the domain rescan functionality, I've realized that I'm unsure what to do with any disks that are detected on the domain. Should I add them back into the database to be listed as floating disks, or should I just return a list of disk images to be attached to whatever the caller of the query needs?
- Ricky
i'm not sure they should be added automatically. I think a dialog[1] showing orphan disks/images on the storage domain for user to choose which to import as 'floating' disks would be better than auto importing them.
there is also the reverse of flagging existing disks as 'missing' in storage?
Perhaps we should start a feature page to discuss and better scope it. There is a feature page that we could expand, it doesn't discuss the notion of importing those disks which is certainly something we need to address.
The original idea was to scan the storage domains and compare the images lists to the database, thus getting a list of images no longer relevant and scrubbing the storage. This will actually be addressed properly in the future (Ayal can elaborate on that) but for now this is needed at least for that use case.
As I understand, the conversation here is about trying to take an already populated SD (from another setup I suppose), scanning it and putting it into RHEV?
As I understood it, the purpose of this functionality wasn't to find images which should be removed from storage, but to find images on the domain that oVirt was unaware of and importing them for use (for instance, if a disk was created outside of oVirt on the domain). If one of the use cases for this feature is also the orphaned images mentioned on the feature page, that may expand the functionality into a separate domain scrub and storage import, both of which would call the rescan (meaning the rescan would not actually add to the database, but instead return a list of "orphaned" disk images). Another solution would be to import all disk images into the database either way, and let the user delete any orphaned images from the GUI.
[1] or a subtab on the storage domain.
_______________________________________________ Engine-devel mailing list Engine-devel@ovirt.org http://lists.ovirt.org/mailman/listinfo/engine-devel
--
Regards,
Dan Yasny Red Hat Israel +972 9769 2280
----- Original Message -----
From: "Ricky Hopper" <Ricky.Hopper@netapp.com> To: "Dan Yasny" <dyasny@redhat.com>, "Andrew Cathrow" <acathrow@redhat.com> Cc: engine-devel@ovirt.org, "Itamar Heim" <iheim@redhat.com>, "Ricky Hopper" <Ricky.Hopper@netapp.com> Sent: Wednesday, 1 August, 2012 4:34:53 PM Subject: Re: [Engine-devel] Domain rescan action question
On 8/1/12 5:59 AM, "Dan Yasny" <dyasny@redhat.com> wrote:
----- Original Message -----
From: "Andrew Cathrow" <acathrow@redhat.com> To: "Itamar Heim" <iheim@redhat.com>, "Dan Yasny" <dyasny@redhat.com>, "Ricky Hopper" <Ricky.Hopper@netapp.com> Cc: engine-devel@ovirt.org Sent: Wednesday, 1 August, 2012 12:24:42 AM Subject: Re: [Engine-devel] Domain rescan action question
----- Original Message -----
From: "Itamar Heim" <iheim@redhat.com> To: "Ricky Hopper" <Ricky.Hopper@netapp.com> Cc: engine-devel@ovirt.org Sent: Tuesday, July 31, 2012 4:44:34 PM Subject: Re: [Engine-devel] Domain rescan action question
On 07/31/2012 11:30 PM, Hopper, Ricky wrote:
Hey all,
As I'm making progress with the domain rescan functionality, I've realized that I'm unsure what to do with any disks that are detected on the domain. Should I add them back into the database to be listed as floating disks, or should I just return a list of disk images to be attached to whatever the caller of the query needs?
- Ricky
i'm not sure they should be added automatically. I think a dialog[1] showing orphan disks/images on the storage domain for user to choose which to import as 'floating' disks would be better than auto importing them.
there is also the reverse of flagging existing disks as 'missing' in storage?
Perhaps we should start a feature page to discuss and better scope it. There is a feature page that we could expand, it doesn't discuss the notion of importing those disks which is certainly something we need to address.
The original idea was to scan the storage domains and compare the images lists to the database, thus getting a list of images no longer relevant and scrubbing the storage. This will actually be addressed properly in the future (Ayal can elaborate on that) but for now this is needed at least for that use case.
As I understand, the conversation here is about trying to take an already populated SD (from another setup I suppose), scanning it and putting it into RHEV?
As I understood it, the purpose of this functionality wasn't to find images which should be removed from storage, but to find images on the domain that oVirt was unaware of and importing them for use (for instance, if a disk was created outside of oVirt on the domain). If one of the use cases for this feature is also the orphaned images mentioned on the feature page, that may expand the functionality into a separate domain scrub and storage import, both of which would call the rescan (meaning the rescan would not actually add to the database, but instead return a list of "orphaned" disk images).
Another solution would be to import all disk images into the database either way, and let the user delete any orphaned images from the GUI.
I think are nice to have, but the problem with the scanning is that if we're not scanning a master domain or an export domain, all we will see is a bunch of images with no context or even hints as to where they belong. The data that makes it all usable is in the engine database and in the ovf files on the master domain. This is why I stopped at the orphaned images part of the feature - because there it's feasible, I would rely on the engine database for image ID comparisons. If we present a user with a list of nameless disks, I doubt it will be of any use.
[1] or a subtab on the storage domain.
_______________________________________________ Engine-devel mailing list Engine-devel@ovirt.org http://lists.ovirt.org/mailman/listinfo/engine-devel
--
Regards,
Dan Yasny Red Hat Israel +972 9769 2280
-- Regards, Dan Yasny Red Hat Israel +972 9769 2280
On 8/1/12 9:42 AM, "Dan Yasny" <dyasny@redhat.com> wrote:
----- Original Message -----
From: "Ricky Hopper" <Ricky.Hopper@netapp.com> To: "Dan Yasny" <dyasny@redhat.com>, "Andrew Cathrow" <acathrow@redhat.com> Cc: engine-devel@ovirt.org, "Itamar Heim" <iheim@redhat.com>, "Ricky Hopper" <Ricky.Hopper@netapp.com> Sent: Wednesday, 1 August, 2012 4:34:53 PM Subject: Re: [Engine-devel] Domain rescan action question
On 8/1/12 5:59 AM, "Dan Yasny" <dyasny@redhat.com> wrote:
----- Original Message -----
From: "Andrew Cathrow" <acathrow@redhat.com> To: "Itamar Heim" <iheim@redhat.com>, "Dan Yasny" <dyasny@redhat.com>, "Ricky Hopper" <Ricky.Hopper@netapp.com> Cc: engine-devel@ovirt.org Sent: Wednesday, 1 August, 2012 12:24:42 AM Subject: Re: [Engine-devel] Domain rescan action question
----- Original Message -----
From: "Itamar Heim" <iheim@redhat.com> To: "Ricky Hopper" <Ricky.Hopper@netapp.com> Cc: engine-devel@ovirt.org Sent: Tuesday, July 31, 2012 4:44:34 PM Subject: Re: [Engine-devel] Domain rescan action question
On 07/31/2012 11:30 PM, Hopper, Ricky wrote:
Hey all,
As I'm making progress with the domain rescan functionality, I've realized that I'm unsure what to do with any disks that are detected on the domain. Should I add them back into the database to be listed as floating disks, or should I just return a list of disk images to be attached to whatever the caller of the query needs?
- Ricky
i'm not sure they should be added automatically. I think a dialog[1] showing orphan disks/images on the storage domain for user to choose which to import as 'floating' disks would be better than auto importing them.
there is also the reverse of flagging existing disks as 'missing' in storage?
Perhaps we should start a feature page to discuss and better scope it. There is a feature page that we could expand, it doesn't discuss the notion of importing those disks which is certainly something we need to address.
The original idea was to scan the storage domains and compare the images lists to the database, thus getting a list of images no longer relevant and scrubbing the storage. This will actually be addressed properly in the future (Ayal can elaborate on that) but for now this is needed at least for that use case.
As I understand, the conversation here is about trying to take an already populated SD (from another setup I suppose), scanning it and putting it into RHEV?
As I understood it, the purpose of this functionality wasn't to find images which should be removed from storage, but to find images on the domain that oVirt was unaware of and importing them for use (for instance, if a disk was created outside of oVirt on the domain). If one of the use cases for this feature is also the orphaned images mentioned on the feature page, that may expand the functionality into a separate domain scrub and storage import, both of which would call the rescan (meaning the rescan would not actually add to the database, but instead return a list of "orphaned" disk images).
Another solution would be to import all disk images into the database either way, and let the user delete any orphaned images from the GUI.
I think are nice to have, but the problem with the scanning is that if we're not scanning a master domain or an export domain, all we will see is a bunch of images with no context or even hints as to where they belong. The data that makes it all usable is in the engine database and in the ovf files on the master domain.
This is why I stopped at the orphaned images part of the feature - because there it's feasible, I would rely on the engine database for image ID comparisons.
If we present a user with a list of nameless disks, I doubt it will be of any use.
The way this would work is by comparing a list of disk images from vdsm and from oVirt's database, finding the ones vdsm returns that oVirt doesn't have, and then either adding or returning those images. So oVirt's db will be used in the comparison. As far as presenting the user with nameless disks, that's a point I hadn't considered; we could generate some sort of placeholder metadata upon addition to show the user that these are new/orphaned disks that were found on the storage domain. Is it safe to assume that the disks discovered by this feature won't be attached to anything?
[1] or a subtab on the storage domain.
_______________________________________________ Engine-devel mailing list Engine-devel@ovirt.org http://lists.ovirt.org/mailman/listinfo/engine-devel
--
Regards,
Dan Yasny Red Hat Israel +972 9769 2280
--
Regards,
Dan Yasny Red Hat Israel +972 9769 2280
----- Original Message -----
From: "Ricky Hopper" <Ricky.Hopper@netapp.com> To: "Dan Yasny" <dyasny@redhat.com> Cc: engine-devel@ovirt.org, "Itamar Heim" <iheim@redhat.com>, "Andrew Cathrow" <acathrow@redhat.com> Sent: Wednesday, 1 August, 2012 4:56:45 PM Subject: Re: [Engine-devel] Domain rescan action question
On 8/1/12 9:42 AM, "Dan Yasny" <dyasny@redhat.com> wrote:
----- Original Message -----
From: "Ricky Hopper" <Ricky.Hopper@netapp.com> To: "Dan Yasny" <dyasny@redhat.com>, "Andrew Cathrow" <acathrow@redhat.com> Cc: engine-devel@ovirt.org, "Itamar Heim" <iheim@redhat.com>, "Ricky Hopper" <Ricky.Hopper@netapp.com> Sent: Wednesday, 1 August, 2012 4:34:53 PM Subject: Re: [Engine-devel] Domain rescan action question
On 8/1/12 5:59 AM, "Dan Yasny" <dyasny@redhat.com> wrote:
----- Original Message -----
From: "Andrew Cathrow" <acathrow@redhat.com> To: "Itamar Heim" <iheim@redhat.com>, "Dan Yasny" <dyasny@redhat.com>, "Ricky Hopper" <Ricky.Hopper@netapp.com> Cc: engine-devel@ovirt.org Sent: Wednesday, 1 August, 2012 12:24:42 AM Subject: Re: [Engine-devel] Domain rescan action question
----- Original Message -----
From: "Itamar Heim" <iheim@redhat.com> To: "Ricky Hopper" <Ricky.Hopper@netapp.com> Cc: engine-devel@ovirt.org Sent: Tuesday, July 31, 2012 4:44:34 PM Subject: Re: [Engine-devel] Domain rescan action question
On 07/31/2012 11:30 PM, Hopper, Ricky wrote: > Hey all, > > As I'm making progress with the domain rescan > functionality, > I've > realized that I'm unsure what to do with any disks that are > detected on > the domain. Should I add them back into the database to be > listed > as > floating disks, or should I just return a list of disk > images > to > be > attached to whatever the caller of the query needs? > > - Ricky
i'm not sure they should be added automatically. I think a dialog[1] showing orphan disks/images on the storage domain for user to choose which to import as 'floating' disks would be better than auto importing them.
there is also the reverse of flagging existing disks as 'missing' in storage?
Perhaps we should start a feature page to discuss and better scope it. There is a feature page that we could expand, it doesn't discuss the notion of importing those disks which is certainly something we need to address.
The original idea was to scan the storage domains and compare the images lists to the database, thus getting a list of images no longer relevant and scrubbing the storage. This will actually be addressed properly in the future (Ayal can elaborate on that) but for now this is needed at least for that use case.
As I understand, the conversation here is about trying to take an already populated SD (from another setup I suppose), scanning it and putting it into RHEV?
As I understood it, the purpose of this functionality wasn't to find images which should be removed from storage, but to find images on the domain that oVirt was unaware of and importing them for use (for instance, if a disk was created outside of oVirt on the domain). If one of the use cases for this feature is also the orphaned images mentioned on the feature page, that may expand the functionality into a separate domain scrub and storage import, both of which would call the rescan (meaning the rescan would not actually add to the database, but instead return a list of "orphaned" disk images).
Another solution would be to import all disk images into the database either way, and let the user delete any orphaned images from the GUI.
I think are nice to have, but the problem with the scanning is that if we're not scanning a master domain or an export domain, all we will see is a bunch of images with no context or even hints as to where they belong. The data that makes it all usable is in the engine database and in the ovf files on the master domain.
This is why I stopped at the orphaned images part of the feature - because there it's feasible, I would rely on the engine database for image ID comparisons.
If we present a user with a list of nameless disks, I doubt it will be of any use.
The way this would work is by comparing a list of disk images from vdsm and from oVirt's database, finding the ones vdsm returns that oVirt doesn't have, and then either adding or returning those images. So oVirt's db will be used in the comparison.
This will work only when scanning storage domains already attached and in use by the current oVirt setup. What I am talking about is what will happen if a LUN that used to be a SD in another oVirt setup is discovered and scanned, with no engine db to compare with. If we don't consider such a use case, life is definitely quite easy, and we're basically within the scope of the orphaned images feature
As far as presenting the user with nameless disks, that's a point I hadn't considered; we could generate some sort of placeholder metadata upon addition to show the user that these are new/orphaned disks that were found on the storage domain. Is it safe to assume that the disks discovered by this feature won't be attached to anything?
The oVirt paradigm says "if it isn't in the engine db, it's not ours", so any LV or image we discover that is missing from the DB or the snapshot chain of the image in the DB, is nameless, and orphaned. Such an image on a current SD, belonging to a working oVirt setup is definitely an orphaned image. Attaching these to VMs is usually also useless, because they are more often than not discarded snapshots that didn't get discarded cleanly for some reason. Now, if we want to make this usable, we might want to actually check the qcow2 metadata of the image to see whether it's a mid-chain snapshot (and if so it's probably just a candidate for cleanup), or a standalone qcow2 or raw image, and then we can move on with the virt-* tools, to find out the image size and the filesystems it contains. This will at least provide the user with some usable information about the detected image. If we're talking about scanning an SD that doesn't presently belong to the current oVirt setup, then this is even more relevant, because all of the images will have no VM-related context.
[1] or a subtab on the storage domain.
_______________________________________________ Engine-devel mailing list Engine-devel@ovirt.org http://lists.ovirt.org/mailman/listinfo/engine-devel
--
Regards,
Dan Yasny Red Hat Israel +972 9769 2280
--
Regards,
Dan Yasny Red Hat Israel +972 9769 2280
-- Regards, Dan Yasny Red Hat Israel +972 9769 2280
On 8/1/12 10:05 AM, "Dan Yasny" <dyasny@redhat.com> wrote:
----- Original Message -----
From: "Ricky Hopper" <Ricky.Hopper@netapp.com> To: "Dan Yasny" <dyasny@redhat.com> Cc: engine-devel@ovirt.org, "Itamar Heim" <iheim@redhat.com>, "Andrew Cathrow" <acathrow@redhat.com> Sent: Wednesday, 1 August, 2012 4:56:45 PM Subject: Re: [Engine-devel] Domain rescan action question
On 8/1/12 9:42 AM, "Dan Yasny" <dyasny@redhat.com> wrote:
----- Original Message -----
From: "Ricky Hopper" <Ricky.Hopper@netapp.com> To: "Dan Yasny" <dyasny@redhat.com>, "Andrew Cathrow" <acathrow@redhat.com> Cc: engine-devel@ovirt.org, "Itamar Heim" <iheim@redhat.com>, "Ricky Hopper" <Ricky.Hopper@netapp.com> Sent: Wednesday, 1 August, 2012 4:34:53 PM Subject: Re: [Engine-devel] Domain rescan action question
On 8/1/12 5:59 AM, "Dan Yasny" <dyasny@redhat.com> wrote:
----- Original Message -----
From: "Andrew Cathrow" <acathrow@redhat.com> To: "Itamar Heim" <iheim@redhat.com>, "Dan Yasny" <dyasny@redhat.com>, "Ricky Hopper" <Ricky.Hopper@netapp.com> Cc: engine-devel@ovirt.org Sent: Wednesday, 1 August, 2012 12:24:42 AM Subject: Re: [Engine-devel] Domain rescan action question
----- Original Message ----- > From: "Itamar Heim" <iheim@redhat.com> > To: "Ricky Hopper" <Ricky.Hopper@netapp.com> > Cc: engine-devel@ovirt.org > Sent: Tuesday, July 31, 2012 4:44:34 PM > Subject: Re: [Engine-devel] Domain rescan action question > > On 07/31/2012 11:30 PM, Hopper, Ricky wrote: > > Hey all, > > > > As I'm making progress with the domain rescan > > functionality, > > I've > > realized that I'm unsure what to do with any disks that are > > detected on > > the domain. Should I add them back into the database to be > > listed > > as > > floating disks, or should I just return a list of disk > > images > > to > > be > > attached to whatever the caller of the query needs? > > > > - Ricky > > i'm not sure they should be added automatically. > I think a dialog[1] showing orphan disks/images on the > storage > domain > for user to choose which to import as 'floating' disks would > be > better > than auto importing them. > > there is also the reverse of flagging existing disks as > 'missing' > in > storage? >
Perhaps we should start a feature page to discuss and better scope it. There is a feature page that we could expand, it doesn't discuss the notion of importing those disks which is certainly something we need to address.
The original idea was to scan the storage domains and compare the images lists to the database, thus getting a list of images no longer relevant and scrubbing the storage. This will actually be addressed properly in the future (Ayal can elaborate on that) but for now this is needed at least for that use case.
As I understand, the conversation here is about trying to take an already populated SD (from another setup I suppose), scanning it and putting it into RHEV?
As I understood it, the purpose of this functionality wasn't to find images which should be removed from storage, but to find images on the domain that oVirt was unaware of and importing them for use (for instance, if a disk was created outside of oVirt on the domain). If one of the use cases for this feature is also the orphaned images mentioned on the feature page, that may expand the functionality into a separate domain scrub and storage import, both of which would call the rescan (meaning the rescan would not actually add to the database, but instead return a list of "orphaned" disk images).
Another solution would be to import all disk images into the database either way, and let the user delete any orphaned images from the GUI.
I think are nice to have, but the problem with the scanning is that if we're not scanning a master domain or an export domain, all we will see is a bunch of images with no context or even hints as to where they belong. The data that makes it all usable is in the engine database and in the ovf files on the master domain.
This is why I stopped at the orphaned images part of the feature - because there it's feasible, I would rely on the engine database for image ID comparisons.
If we present a user with a list of nameless disks, I doubt it will be of any use.
The way this would work is by comparing a list of disk images from vdsm and from oVirt's database, finding the ones vdsm returns that oVirt doesn't have, and then either adding or returning those images. So oVirt's db will be used in the comparison.
This will work only when scanning storage domains already attached and in use by the current oVirt setup. What I am talking about is what will happen if a LUN that used to be a SD in another oVirt setup is discovered and scanned, with no engine db to compare with. If we don't consider such a use case, life is definitely quite easy, and we're basically within the scope of the orphaned images feature
This use case should definitely be considered, maybe have a separate case where the rescan would return all "compatible" disks (i.e. disks that aren't just partial snapshots and the like) if the domain has not yet been mounted. Essentially, it would run the same comparison, but compare against an empty list rather than a list of disks. There's no way it's as simple as that (I'm unsure of the methods oVirt uses to mount a domain), but it's a good starting point.
As far as presenting the user with nameless disks, that's a point I hadn't considered; we could generate some sort of placeholder metadata upon addition to show the user that these are new/orphaned disks that were found on the storage domain. Is it safe to assume that the disks discovered by this feature won't be attached to anything?
The oVirt paradigm says "if it isn't in the engine db, it's not ours", so any LV or image we discover that is missing from the DB or the snapshot chain of the image in the DB, is nameless, and orphaned.
Such an image on a current SD, belonging to a working oVirt setup is definitely an orphaned image. Attaching these to VMs is usually also useless, because they are more often than not discarded snapshots that didn't get discarded cleanly for some reason.
Now, if we want to make this usable, we might want to actually check the qcow2 metadata of the image to see whether it's a mid-chain snapshot (and if so it's probably just a candidate for cleanup), or a standalone qcow2 or raw image, and then we can move on with the virt-* tools, to find out the image size and the filesystems it contains. This will at least provide the user with some usable information about the detected image. If we're talking about scanning an SD that doesn't presently belong to the current oVirt setup, then this is even more relevant, because all of the images will have no VM-related context.
We're currently working on having disks created outside of the oVirt environment, so not all orphaned disks on the existing storage domain will be artifacts of supposedly-deleted data. For our use case, disk images created by us will be able to be imported into oVirt and attached to a VM created through the engine. Because of this, saying "if it isn't in the engine db, it's not ours" wouldn't necessarily be true. When you talk about checking the metadata, does either oVirt or vdsm have a simple way to do this? A query of some sort would be ideal for this, as it could be run for each image as a qualifier for import. Also, as far as writing the functionality itself, I'm gathering that it should be structured as a query to return these orphaned images, which can then be acted upon/added to the database through a separate command after checking the validity of each image?
> > [1] or a subtab on the storage domain. > > _______________________________________________ > Engine-devel mailing list > Engine-devel@ovirt.org > http://lists.ovirt.org/mailman/listinfo/engine-devel >
--
Regards,
Dan Yasny Red Hat Israel +972 9769 2280
--
Regards,
Dan Yasny Red Hat Israel +972 9769 2280
--
Regards,
Dan Yasny Red Hat Israel +972 9769 2280
----- Original Message -----
From: "Ricky Hopper" <Ricky.Hopper@netapp.com> To: "Dan Yasny" <dyasny@redhat.com> Cc: engine-devel@ovirt.org, "Itamar Heim" <iheim@redhat.com>, "Andrew Cathrow" <acathrow@redhat.com> Sent: Wednesday, 1 August, 2012 8:36:09 PM Subject: Re: [Engine-devel] Domain rescan action question
On 8/1/12 10:05 AM, "Dan Yasny" <dyasny@redhat.com> wrote:
----- Original Message -----
From: "Ricky Hopper" <Ricky.Hopper@netapp.com> To: "Dan Yasny" <dyasny@redhat.com> Cc: engine-devel@ovirt.org, "Itamar Heim" <iheim@redhat.com>, "Andrew Cathrow" <acathrow@redhat.com> Sent: Wednesday, 1 August, 2012 4:56:45 PM Subject: Re: [Engine-devel] Domain rescan action question
On 8/1/12 9:42 AM, "Dan Yasny" <dyasny@redhat.com> wrote:
----- Original Message -----
From: "Ricky Hopper" <Ricky.Hopper@netapp.com> To: "Dan Yasny" <dyasny@redhat.com>, "Andrew Cathrow" <acathrow@redhat.com> Cc: engine-devel@ovirt.org, "Itamar Heim" <iheim@redhat.com>, "Ricky Hopper" <Ricky.Hopper@netapp.com> Sent: Wednesday, 1 August, 2012 4:34:53 PM Subject: Re: [Engine-devel] Domain rescan action question
On 8/1/12 5:59 AM, "Dan Yasny" <dyasny@redhat.com> wrote:
----- Original Message ----- > From: "Andrew Cathrow" <acathrow@redhat.com> > To: "Itamar Heim" <iheim@redhat.com>, "Dan Yasny" > <dyasny@redhat.com>, >"Ricky Hopper" <Ricky.Hopper@netapp.com> > Cc: engine-devel@ovirt.org > Sent: Wednesday, 1 August, 2012 12:24:42 AM > Subject: Re: [Engine-devel] Domain rescan action question > > > > ----- Original Message ----- > > From: "Itamar Heim" <iheim@redhat.com> > > To: "Ricky Hopper" <Ricky.Hopper@netapp.com> > > Cc: engine-devel@ovirt.org > > Sent: Tuesday, July 31, 2012 4:44:34 PM > > Subject: Re: [Engine-devel] Domain rescan action question > > > > On 07/31/2012 11:30 PM, Hopper, Ricky wrote: > > > Hey all, > > > > > > As I'm making progress with the domain rescan > > > functionality, > > > I've > > > realized that I'm unsure what to do with any disks that > > > are > > > detected on > > > the domain. Should I add them back into the database to > > > be > > > listed > > > as > > > floating disks, or should I just return a list of disk > > > images > > > to > > > be > > > attached to whatever the caller of the query needs? > > > > > > - Ricky > > > > i'm not sure they should be added automatically. > > I think a dialog[1] showing orphan disks/images on the > > storage > > domain > > for user to choose which to import as 'floating' disks > > would > > be > > better > > than auto importing them. > > > > there is also the reverse of flagging existing disks as > > 'missing' > > in > > storage? > > > > Perhaps we should start a feature page to discuss and better > scope > it. > There is a feature page that we could expand, it doesn't > discuss > the > notion of importing those disks which is certainly something > we > need > to address. > > > http://wiki.ovirt.org/wiki/Features/Orphaned_Images
The original idea was to scan the storage domains and compare the images lists to the database, thus getting a list of images no longer relevant and scrubbing the storage. This will actually be addressed properly in the future (Ayal can elaborate on that) but for now this is needed at least for that use case.
As I understand, the conversation here is about trying to take an already populated SD (from another setup I suppose), scanning it and putting it into RHEV?
As I understood it, the purpose of this functionality wasn't to find images which should be removed from storage, but to find images on the domain that oVirt was unaware of and importing them for use (for instance, if a disk was created outside of oVirt on the domain). If one of the use cases for this feature is also the orphaned images mentioned on the feature page, that may expand the functionality into a separate domain scrub and storage import, both of which would call the rescan (meaning the rescan would not actually add to the database, but instead return a list of "orphaned" disk images).
Another solution would be to import all disk images into the database either way, and let the user delete any orphaned images from the GUI.
I think are nice to have, but the problem with the scanning is that if we're not scanning a master domain or an export domain, all we will see is a bunch of images with no context or even hints as to where they belong. The data that makes it all usable is in the engine database and in the ovf files on the master domain.
This is why I stopped at the orphaned images part of the feature - because there it's feasible, I would rely on the engine database for image ID comparisons.
If we present a user with a list of nameless disks, I doubt it will be of any use.
The way this would work is by comparing a list of disk images from vdsm and from oVirt's database, finding the ones vdsm returns that oVirt doesn't have, and then either adding or returning those images. So oVirt's db will be used in the comparison.
This will work only when scanning storage domains already attached and in use by the current oVirt setup. What I am talking about is what will happen if a LUN that used to be a SD in another oVirt setup is discovered and scanned, with no engine db to compare with. If we don't consider such a use case, life is definitely quite easy, and we're basically within the scope of the orphaned images feature
This use case should definitely be considered, maybe have a separate case where the rescan would return all "compatible" disks (i.e. disks that aren't just partial snapshots and the like) if the domain has not yet been mounted. Essentially, it would run the same comparison, but compare against an empty list rather than a list of disks. There's no way it's as simple as that (I'm unsure of the methods oVirt uses to mount a domain), but it's a good starting point.
There is no complex method there. For file storage it's just a mount command, and for block it's LVM (plus iscsi session establishment, if needed)
As far as presenting the user with nameless disks, that's a point I hadn't considered; we could generate some sort of placeholder metadata upon addition to show the user that these are new/orphaned disks that were found on the storage domain. Is it safe to assume that the disks discovered by this feature won't be attached to anything?
The oVirt paradigm says "if it isn't in the engine db, it's not ours", so any LV or image we discover that is missing from the DB or the snapshot chain of the image in the DB, is nameless, and orphaned.
Such an image on a current SD, belonging to a working oVirt setup is definitely an orphaned image. Attaching these to VMs is usually also useless, because they are more often than not discarded snapshots that didn't get discarded cleanly for some reason.
Now, if we want to make this usable, we might want to actually check the qcow2 metadata of the image to see whether it's a mid-chain snapshot (and if so it's probably just a candidate for cleanup), or a standalone qcow2 or raw image, and then we can move on with the virt-* tools, to find out the image size and the filesystems it contains. This will at least provide the user with some usable information about the detected image. If we're talking about scanning an SD that doesn't presently belong to the current oVirt setup, then this is even more relevant, because all of the images will have no VM-related context.
We're currently working on having disks created outside of the oVirt environment, so not all orphaned disks on the existing storage domain will be artifacts of supposedly-deleted data.
Do you mean like rhevm-image-upload, or something different?
For our use case, disk images created by us will be able to be imported into oVirt and attached to a VM created through the engine. Because of this, saying "if it isn't in the engine db, it's not ours" wouldn't necessarily be true.
When you talk about checking the metadata, does either oVirt or vdsm have a simple way to do this? A query of some sort would be ideal for this, as it could be run for each image as a qualifier for import.
qemu-img info and libguestfs commands should do. Besides, our images do come with some metadata (in the LVM tags or a .meta file)
Also, as far as writing the functionality itself, I'm gathering that it should be structured as a query to return these orphaned images, which can then be acted upon/added to the database through a separate command after checking the validity of each image?
Yes, a simple way to say "import this one to DB, attach to VM X or make floating", "delete that one", "skip"
> > > > > [1] or a subtab on the storage domain. > > > > _______________________________________________ > > Engine-devel mailing list > > Engine-devel@ovirt.org > > http://lists.ovirt.org/mailman/listinfo/engine-devel > > >
--
Regards,
Dan Yasny Red Hat Israel +972 9769 2280
--
Regards,
Dan Yasny Red Hat Israel +972 9769 2280
--
Regards,
Dan Yasny Red Hat Israel +972 9769 2280
-- Regards, Dan Yasny Red Hat Israel +972 9769 2280
In the interest of good discussion, we've put up a feature page for this feature (http://wiki.ovirt.org/wiki/Features/Domain_Scan), which links to a talk page where modifications can be proposed to how I've laid out the feature. So far, it covers how the query works and which commands will come about to implement it. I'd appreciate it if anyone concerned could check this out and make any changes as they see fit so we can get going with the coding. - Ricky On 8/1/12 2:35 PM, "Dan Yasny" <dyasny@redhat.com> wrote:
----- Original Message -----
From: "Ricky Hopper" <Ricky.Hopper@netapp.com> To: "Dan Yasny" <dyasny@redhat.com> Cc: engine-devel@ovirt.org, "Itamar Heim" <iheim@redhat.com>, "Andrew Cathrow" <acathrow@redhat.com> Sent: Wednesday, 1 August, 2012 8:36:09 PM Subject: Re: [Engine-devel] Domain rescan action question
On 8/1/12 10:05 AM, "Dan Yasny" <dyasny@redhat.com> wrote:
----- Original Message -----
From: "Ricky Hopper" <Ricky.Hopper@netapp.com> To: "Dan Yasny" <dyasny@redhat.com> Cc: engine-devel@ovirt.org, "Itamar Heim" <iheim@redhat.com>, "Andrew Cathrow" <acathrow@redhat.com> Sent: Wednesday, 1 August, 2012 4:56:45 PM Subject: Re: [Engine-devel] Domain rescan action question
On 8/1/12 9:42 AM, "Dan Yasny" <dyasny@redhat.com> wrote:
----- Original Message -----
From: "Ricky Hopper" <Ricky.Hopper@netapp.com> To: "Dan Yasny" <dyasny@redhat.com>, "Andrew Cathrow" <acathrow@redhat.com> Cc: engine-devel@ovirt.org, "Itamar Heim" <iheim@redhat.com>, "Ricky Hopper" <Ricky.Hopper@netapp.com> Sent: Wednesday, 1 August, 2012 4:34:53 PM Subject: Re: [Engine-devel] Domain rescan action question
On 8/1/12 5:59 AM, "Dan Yasny" <dyasny@redhat.com> wrote:
> > >----- Original Message ----- >> From: "Andrew Cathrow" <acathrow@redhat.com> >> To: "Itamar Heim" <iheim@redhat.com>, "Dan Yasny" >> <dyasny@redhat.com>, >>"Ricky Hopper" <Ricky.Hopper@netapp.com> >> Cc: engine-devel@ovirt.org >> Sent: Wednesday, 1 August, 2012 12:24:42 AM >> Subject: Re: [Engine-devel] Domain rescan action question >> >> >> >> ----- Original Message ----- >> > From: "Itamar Heim" <iheim@redhat.com> >> > To: "Ricky Hopper" <Ricky.Hopper@netapp.com> >> > Cc: engine-devel@ovirt.org >> > Sent: Tuesday, July 31, 2012 4:44:34 PM >> > Subject: Re: [Engine-devel] Domain rescan action question >> > >> > On 07/31/2012 11:30 PM, Hopper, Ricky wrote: >> > > Hey all, >> > > >> > > As I'm making progress with the domain rescan >> > > functionality, >> > > I've >> > > realized that I'm unsure what to do with any disks that >> > > are >> > > detected on >> > > the domain. Should I add them back into the database to >> > > be >> > > listed >> > > as >> > > floating disks, or should I just return a list of disk >> > > images >> > > to >> > > be >> > > attached to whatever the caller of the query needs? >> > > >> > > - Ricky >> > >> > i'm not sure they should be added automatically. >> > I think a dialog[1] showing orphan disks/images on the >> > storage >> > domain >> > for user to choose which to import as 'floating' disks >> > would >> > be >> > better >> > than auto importing them. >> > >> > there is also the reverse of flagging existing disks as >> > 'missing' >> > in >> > storage? >> > >> >> Perhaps we should start a feature page to discuss and better >> scope >> it. >> There is a feature page that we could expand, it doesn't >> discuss >> the >> notion of importing those disks which is certainly something >> we >> need >> to address. >> >> >> http://wiki.ovirt.org/wiki/Features/Orphaned_Images > >The original idea was to scan the storage domains and compare >the >images >lists to the database, thus getting a list of images no longer >relevant >and scrubbing the storage. This will actually be addressed >properly >in >the future (Ayal can elaborate on that) but for now this is >needed >at >least for that use case. > > >As I understand, the conversation here is about trying to take >an >already >populated SD (from another setup I suppose), scanning it and >putting >it >into RHEV?
As I understood it, the purpose of this functionality wasn't to find images which should be removed from storage, but to find images on the domain that oVirt was unaware of and importing them for use (for instance, if a disk was created outside of oVirt on the domain). If one of the use cases for this feature is also the orphaned images mentioned on the feature page, that may expand the functionality into a separate domain scrub and storage import, both of which would call the rescan (meaning the rescan would not actually add to the database, but instead return a list of "orphaned" disk images).
Another solution would be to import all disk images into the database either way, and let the user delete any orphaned images from the GUI.
I think are nice to have, but the problem with the scanning is that if we're not scanning a master domain or an export domain, all we will see is a bunch of images with no context or even hints as to where they belong. The data that makes it all usable is in the engine database and in the ovf files on the master domain.
This is why I stopped at the orphaned images part of the feature - because there it's feasible, I would rely on the engine database for image ID comparisons.
If we present a user with a list of nameless disks, I doubt it will be of any use.
The way this would work is by comparing a list of disk images from vdsm and from oVirt's database, finding the ones vdsm returns that oVirt doesn't have, and then either adding or returning those images. So oVirt's db will be used in the comparison.
This will work only when scanning storage domains already attached and in use by the current oVirt setup. What I am talking about is what will happen if a LUN that used to be a SD in another oVirt setup is discovered and scanned, with no engine db to compare with. If we don't consider such a use case, life is definitely quite easy, and we're basically within the scope of the orphaned images feature
This use case should definitely be considered, maybe have a separate case where the rescan would return all "compatible" disks (i.e. disks that aren't just partial snapshots and the like) if the domain has not yet been mounted. Essentially, it would run the same comparison, but compare against an empty list rather than a list of disks. There's no way it's as simple as that (I'm unsure of the methods oVirt uses to mount a domain), but it's a good starting point.
There is no complex method there. For file storage it's just a mount command, and for block it's LVM (plus iscsi session establishment, if needed)
As far as presenting the user with nameless disks, that's a point I hadn't considered; we could generate some sort of placeholder metadata upon addition to show the user that these are new/orphaned disks that were found on the storage domain. Is it safe to assume that the disks discovered by this feature won't be attached to anything?
The oVirt paradigm says "if it isn't in the engine db, it's not ours", so any LV or image we discover that is missing from the DB or the snapshot chain of the image in the DB, is nameless, and orphaned.
Such an image on a current SD, belonging to a working oVirt setup is definitely an orphaned image. Attaching these to VMs is usually also useless, because they are more often than not discarded snapshots that didn't get discarded cleanly for some reason.
Now, if we want to make this usable, we might want to actually check the qcow2 metadata of the image to see whether it's a mid-chain snapshot (and if so it's probably just a candidate for cleanup), or a standalone qcow2 or raw image, and then we can move on with the virt-* tools, to find out the image size and the filesystems it contains. This will at least provide the user with some usable information about the detected image. If we're talking about scanning an SD that doesn't presently belong to the current oVirt setup, then this is even more relevant, because all of the images will have no VM-related context.
We're currently working on having disks created outside of the oVirt environment, so not all orphaned disks on the existing storage domain will be artifacts of supposedly-deleted data.
Do you mean like rhevm-image-upload, or something different?
For our use case, disk images created by us will be able to be imported into oVirt and attached to a VM created through the engine. Because of this, saying "if it isn't in the engine db, it's not ours" wouldn't necessarily be true.
When you talk about checking the metadata, does either oVirt or vdsm have a simple way to do this? A query of some sort would be ideal for this, as it could be run for each image as a qualifier for import.
qemu-img info and libguestfs commands should do. Besides, our images do come with some metadata (in the LVM tags or a .meta file)
Also, as far as writing the functionality itself, I'm gathering that it should be structured as a query to return these orphaned images, which can then be acted upon/added to the database through a separate command after checking the validity of each image?
Yes, a simple way to say "import this one to DB, attach to VM X or make floating", "delete that one", "skip"
> >> >> > >> > [1] or a subtab on the storage domain. >> > >> > _______________________________________________ >> > Engine-devel mailing list >> > Engine-devel@ovirt.org >> > http://lists.ovirt.org/mailman/listinfo/engine-devel >> > >> > >-- > > > >Regards, > >Dan Yasny >Red Hat Israel >+972 9769 2280
--
Regards,
Dan Yasny Red Hat Israel +972 9769 2280
--
Regards,
Dan Yasny Red Hat Israel +972 9769 2280
--
Regards,
Dan Yasny Red Hat Israel +972 9769 2280 _______________________________________________ Engine-devel mailing list Engine-devel@ovirt.org http://lists.ovirt.org/mailman/listinfo/engine-devel
Thanks Ricky, I've added reviewing this to my todo list Dan ----- Original Message -----
From: "Ricky Hopper" <Ricky.Hopper@netapp.com> To: "Dan Yasny" <dyasny@redhat.com> Cc: engine-devel@ovirt.org Sent: Thursday, 2 August, 2012 5:37:10 PM Subject: Re: [Engine-devel] Domain rescan action question
In the interest of good discussion, we've put up a feature page for this feature (http://wiki.ovirt.org/wiki/Features/Domain_Scan), which links to a talk page where modifications can be proposed to how I've laid out the feature. So far, it covers how the query works and which commands will come about to implement it. I'd appreciate it if anyone concerned could check this out and make any changes as they see fit so we can get going with the coding.
- Ricky
On 8/1/12 2:35 PM, "Dan Yasny" <dyasny@redhat.com> wrote:
----- Original Message -----
From: "Ricky Hopper" <Ricky.Hopper@netapp.com> To: "Dan Yasny" <dyasny@redhat.com> Cc: engine-devel@ovirt.org, "Itamar Heim" <iheim@redhat.com>, "Andrew Cathrow" <acathrow@redhat.com> Sent: Wednesday, 1 August, 2012 8:36:09 PM Subject: Re: [Engine-devel] Domain rescan action question
On 8/1/12 10:05 AM, "Dan Yasny" <dyasny@redhat.com> wrote:
----- Original Message -----
From: "Ricky Hopper" <Ricky.Hopper@netapp.com> To: "Dan Yasny" <dyasny@redhat.com> Cc: engine-devel@ovirt.org, "Itamar Heim" <iheim@redhat.com>, "Andrew Cathrow" <acathrow@redhat.com> Sent: Wednesday, 1 August, 2012 4:56:45 PM Subject: Re: [Engine-devel] Domain rescan action question
On 8/1/12 9:42 AM, "Dan Yasny" <dyasny@redhat.com> wrote:
----- Original Message ----- > From: "Ricky Hopper" <Ricky.Hopper@netapp.com> > To: "Dan Yasny" <dyasny@redhat.com>, "Andrew Cathrow" ><acathrow@redhat.com> > Cc: engine-devel@ovirt.org, "Itamar Heim" > <iheim@redhat.com>, > "Ricky >Hopper" <Ricky.Hopper@netapp.com> > Sent: Wednesday, 1 August, 2012 4:34:53 PM > Subject: Re: [Engine-devel] Domain rescan action question > > > > On 8/1/12 5:59 AM, "Dan Yasny" <dyasny@redhat.com> wrote: > > > > > > >----- Original Message ----- > >> From: "Andrew Cathrow" <acathrow@redhat.com> > >> To: "Itamar Heim" <iheim@redhat.com>, "Dan Yasny" > >> <dyasny@redhat.com>, > >>"Ricky Hopper" <Ricky.Hopper@netapp.com> > >> Cc: engine-devel@ovirt.org > >> Sent: Wednesday, 1 August, 2012 12:24:42 AM > >> Subject: Re: [Engine-devel] Domain rescan action question > >> > >> > >> > >> ----- Original Message ----- > >> > From: "Itamar Heim" <iheim@redhat.com> > >> > To: "Ricky Hopper" <Ricky.Hopper@netapp.com> > >> > Cc: engine-devel@ovirt.org > >> > Sent: Tuesday, July 31, 2012 4:44:34 PM > >> > Subject: Re: [Engine-devel] Domain rescan action > >> > question > >> > > >> > On 07/31/2012 11:30 PM, Hopper, Ricky wrote: > >> > > Hey all, > >> > > > >> > > As I'm making progress with the domain rescan > >> > > functionality, > >> > > I've > >> > > realized that I'm unsure what to do with any disks > >> > > that > >> > > are > >> > > detected on > >> > > the domain. Should I add them back into the database > >> > > to > >> > > be > >> > > listed > >> > > as > >> > > floating disks, or should I just return a list of > >> > > disk > >> > > images > >> > > to > >> > > be > >> > > attached to whatever the caller of the query needs? > >> > > > >> > > - Ricky > >> > > >> > i'm not sure they should be added automatically. > >> > I think a dialog[1] showing orphan disks/images on the > >> > storage > >> > domain > >> > for user to choose which to import as 'floating' disks > >> > would > >> > be > >> > better > >> > than auto importing them. > >> > > >> > there is also the reverse of flagging existing disks as > >> > 'missing' > >> > in > >> > storage? > >> > > >> > >> Perhaps we should start a feature page to discuss and > >> better > >> scope > >> it. > >> There is a feature page that we could expand, it doesn't > >> discuss > >> the > >> notion of importing those disks which is certainly > >> something > >> we > >> need > >> to address. > >> > >> > >> http://wiki.ovirt.org/wiki/Features/Orphaned_Images > > > >The original idea was to scan the storage domains and > >compare > >the > >images > >lists to the database, thus getting a list of images no > >longer > >relevant > >and scrubbing the storage. This will actually be addressed > >properly > >in > >the future (Ayal can elaborate on that) but for now this is > >needed > >at > >least for that use case. > > > > > >As I understand, the conversation here is about trying to > >take > >an > >already > >populated SD (from another setup I suppose), scanning it > >and > >putting > >it > >into RHEV? > > As I understood it, the purpose of this functionality wasn't > to > find > images which should be removed from storage, but to find > images > on > the > domain that oVirt was unaware of and importing them for use > (for > instance, > if a disk was created outside of oVirt on the domain). If > one > of > the > use > cases for this feature is also the orphaned images mentioned > on > the > feature page, that may expand the functionality into a > separate > domain > scrub and storage import, both of which would call the > rescan > (meaning the > rescan would not actually add to the database, but instead > return > a > list > of "orphaned" disk images). > > Another solution would be to import all disk images into the > database > either way, and let the user delete any orphaned images from > the > GUI.
I think are nice to have, but the problem with the scanning is that if we're not scanning a master domain or an export domain, all we will see is a bunch of images with no context or even hints as to where they belong. The data that makes it all usable is in the engine database and in the ovf files on the master domain.
This is why I stopped at the orphaned images part of the feature - because there it's feasible, I would rely on the engine database for image ID comparisons.
If we present a user with a list of nameless disks, I doubt it will be of any use.
The way this would work is by comparing a list of disk images from vdsm and from oVirt's database, finding the ones vdsm returns that oVirt doesn't have, and then either adding or returning those images. So oVirt's db will be used in the comparison.
This will work only when scanning storage domains already attached and in use by the current oVirt setup. What I am talking about is what will happen if a LUN that used to be a SD in another oVirt setup is discovered and scanned, with no engine db to compare with. If we don't consider such a use case, life is definitely quite easy, and we're basically within the scope of the orphaned images feature
This use case should definitely be considered, maybe have a separate case where the rescan would return all "compatible" disks (i.e. disks that aren't just partial snapshots and the like) if the domain has not yet been mounted. Essentially, it would run the same comparison, but compare against an empty list rather than a list of disks. There's no way it's as simple as that (I'm unsure of the methods oVirt uses to mount a domain), but it's a good starting point.
There is no complex method there. For file storage it's just a mount command, and for block it's LVM (plus iscsi session establishment, if needed)
As far as presenting the user with nameless disks, that's a point I hadn't considered; we could generate some sort of placeholder metadata upon addition to show the user that these are new/orphaned disks that were found on the storage domain. Is it safe to assume that the disks discovered by this feature won't be attached to anything?
The oVirt paradigm says "if it isn't in the engine db, it's not ours", so any LV or image we discover that is missing from the DB or the snapshot chain of the image in the DB, is nameless, and orphaned.
Such an image on a current SD, belonging to a working oVirt setup is definitely an orphaned image. Attaching these to VMs is usually also useless, because they are more often than not discarded snapshots that didn't get discarded cleanly for some reason.
Now, if we want to make this usable, we might want to actually check the qcow2 metadata of the image to see whether it's a mid-chain snapshot (and if so it's probably just a candidate for cleanup), or a standalone qcow2 or raw image, and then we can move on with the virt-* tools, to find out the image size and the filesystems it contains. This will at least provide the user with some usable information about the detected image. If we're talking about scanning an SD that doesn't presently belong to the current oVirt setup, then this is even more relevant, because all of the images will have no VM-related context.
We're currently working on having disks created outside of the oVirt environment, so not all orphaned disks on the existing storage domain will be artifacts of supposedly-deleted data.
Do you mean like rhevm-image-upload, or something different?
For our use case, disk images created by us will be able to be imported into oVirt and attached to a VM created through the engine. Because of this, saying "if it isn't in the engine db, it's not ours" wouldn't necessarily be true.
When you talk about checking the metadata, does either oVirt or vdsm have a simple way to do this? A query of some sort would be ideal for this, as it could be run for each image as a qualifier for import.
qemu-img info and libguestfs commands should do. Besides, our images do come with some metadata (in the LVM tags or a .meta file)
Also, as far as writing the functionality itself, I'm gathering that it should be structured as a query to return these orphaned images, which can then be acted upon/added to the database through a separate command after checking the validity of each image?
Yes, a simple way to say "import this one to DB, attach to VM X or make floating", "delete that one", "skip"
> > > >> > >> > > >> > [1] or a subtab on the storage domain. > >> > > >> > _______________________________________________ > >> > Engine-devel mailing list > >> > Engine-devel@ovirt.org > >> > http://lists.ovirt.org/mailman/listinfo/engine-devel > >> > > >> > > > >-- > > > > > > > >Regards, > > > >Dan Yasny > >Red Hat Israel > >+972 9769 2280 > >
--
Regards,
Dan Yasny Red Hat Israel +972 9769 2280
--
Regards,
Dan Yasny Red Hat Israel +972 9769 2280
--
Regards,
Dan Yasny Red Hat Israel +972 9769 2280 _______________________________________________ Engine-devel mailing list Engine-devel@ovirt.org http://lists.ovirt.org/mailman/listinfo/engine-devel
-- Regards, Dan Yasny Red Hat Israel +972 9769 2280
No comments below. I am just curious how you can have disk created outside of the oVirt environment if the storage domain is mounted on oVirt engine. Does your application try to communicate with VDSM though SPM host to do that? Are the two applications(oVirt engine and your application) coexisting and manipulating the storage domain at the same time or one application is quiet when the other one is functioning? IMHO, modifying the storage domain meta data from two application are dangerous and I suppose your application should know the reason and what these disks are for. So telling oVirt to import the disks automatically should be reasonable because you know what these disks are for and it is unnecessary for the oVirt administrator to select which one to import. On 2012-8-2 1:36, Hopper, Ricky wrote:
On 8/1/12 10:05 AM, "Dan Yasny" <dyasny@redhat.com> wrote:
----- Original Message -----
From: "Ricky Hopper" <Ricky.Hopper@netapp.com> To: "Dan Yasny" <dyasny@redhat.com> Cc: engine-devel@ovirt.org, "Itamar Heim" <iheim@redhat.com>, "Andrew Cathrow" <acathrow@redhat.com> Sent: Wednesday, 1 August, 2012 4:56:45 PM Subject: Re: [Engine-devel] Domain rescan action question
On 8/1/12 9:42 AM, "Dan Yasny" <dyasny@redhat.com> wrote:
----- Original Message -----
From: "Ricky Hopper" <Ricky.Hopper@netapp.com> To: "Dan Yasny" <dyasny@redhat.com>, "Andrew Cathrow" <acathrow@redhat.com> Cc: engine-devel@ovirt.org, "Itamar Heim" <iheim@redhat.com>, "Ricky Hopper" <Ricky.Hopper@netapp.com> Sent: Wednesday, 1 August, 2012 4:34:53 PM Subject: Re: [Engine-devel] Domain rescan action question
On 8/1/12 5:59 AM, "Dan Yasny" <dyasny@redhat.com> wrote:
----- Original Message ----- > From: "Andrew Cathrow" <acathrow@redhat.com> > To: "Itamar Heim" <iheim@redhat.com>, "Dan Yasny" > <dyasny@redhat.com>, > "Ricky Hopper" <Ricky.Hopper@netapp.com> > Cc: engine-devel@ovirt.org > Sent: Wednesday, 1 August, 2012 12:24:42 AM > Subject: Re: [Engine-devel] Domain rescan action question > > > > ----- Original Message ----- >> From: "Itamar Heim" <iheim@redhat.com> >> To: "Ricky Hopper" <Ricky.Hopper@netapp.com> >> Cc: engine-devel@ovirt.org >> Sent: Tuesday, July 31, 2012 4:44:34 PM >> Subject: Re: [Engine-devel] Domain rescan action question >> >> On 07/31/2012 11:30 PM, Hopper, Ricky wrote: >>> Hey all, >>> >>> As I'm making progress with the domain rescan >>> functionality, >>> I've >>> realized that I'm unsure what to do with any disks that are >>> detected on >>> the domain. Should I add them back into the database to be >>> listed >>> as >>> floating disks, or should I just return a list of disk >>> images >>> to >>> be >>> attached to whatever the caller of the query needs? >>> >>> - Ricky >> i'm not sure they should be added automatically. >> I think a dialog[1] showing orphan disks/images on the >> storage >> domain >> for user to choose which to import as 'floating' disks would >> be >> better >> than auto importing them. >> >> there is also the reverse of flagging existing disks as >> 'missing' >> in >> storage? >> > Perhaps we should start a feature page to discuss and better > scope > it. > There is a feature page that we could expand, it doesn't > discuss > the > notion of importing those disks which is certainly something we > need > to address. > > > http://wiki.ovirt.org/wiki/Features/Orphaned_Images The original idea was to scan the storage domains and compare the images lists to the database, thus getting a list of images no longer relevant and scrubbing the storage. This will actually be addressed properly in the future (Ayal can elaborate on that) but for now this is needed at least for that use case.
As I understand, the conversation here is about trying to take an already populated SD (from another setup I suppose), scanning it and putting it into RHEV?
As I understood it, the purpose of this functionality wasn't to find images which should be removed from storage, but to find images on the domain that oVirt was unaware of and importing them for use (for instance, if a disk was created outside of oVirt on the domain). If one of the use cases for this feature is also the orphaned images mentioned on the feature page, that may expand the functionality into a separate domain scrub and storage import, both of which would call the rescan (meaning the rescan would not actually add to the database, but instead return a list of "orphaned" disk images).
Another solution would be to import all disk images into the database either way, and let the user delete any orphaned images from the GUI. I think are nice to have, but the problem with the scanning is that if we're not scanning a master domain or an export domain, all we will see is a bunch of images with no context or even hints as to where they belong. The data that makes it all usable is in the engine database and in the ovf files on the master domain.
This is why I stopped at the orphaned images part of the feature - because there it's feasible, I would rely on the engine database for image ID comparisons.
If we present a user with a list of nameless disks, I doubt it will be of any use.
The way this would work is by comparing a list of disk images from vdsm and from oVirt's database, finding the ones vdsm returns that oVirt doesn't have, and then either adding or returning those images. So oVirt's db will be used in the comparison. This will work only when scanning storage domains already attached and in use by the current oVirt setup. What I am talking about is what will happen if a LUN that used to be a SD in another oVirt setup is discovered and scanned, with no engine db to compare with. If we don't consider such a use case, life is definitely quite easy, and we're basically within the scope of the orphaned images feature
This use case should definitely be considered, maybe have a separate case where the rescan would return all "compatible" disks (i.e. disks that aren't just partial snapshots and the like) if the domain has not yet been mounted. Essentially, it would run the same comparison, but compare against an empty list rather than a list of disks. There's no way it's as simple as that (I'm unsure of the methods oVirt uses to mount a domain), but it's a good starting point.
As far as presenting the user with nameless disks, that's a point I hadn't considered; we could generate some sort of placeholder metadata upon addition to show the user that these are new/orphaned disks that were found on the storage domain. Is it safe to assume that the disks discovered by this feature won't be attached to anything? The oVirt paradigm says "if it isn't in the engine db, it's not ours", so any LV or image we discover that is missing from the DB or the snapshot chain of the image in the DB, is nameless, and orphaned.
Such an image on a current SD, belonging to a working oVirt setup is definitely an orphaned image. Attaching these to VMs is usually also useless, because they are more often than not discarded snapshots that didn't get discarded cleanly for some reason.
Now, if we want to make this usable, we might want to actually check the qcow2 metadata of the image to see whether it's a mid-chain snapshot (and if so it's probably just a candidate for cleanup), or a standalone qcow2 or raw image, and then we can move on with the virt-* tools, to find out the image size and the filesystems it contains. This will at least provide the user with some usable information about the detected image. If we're talking about scanning an SD that doesn't presently belong to the current oVirt setup, then this is even more relevant, because all of the images will have no VM-related context. We're currently working on having disks created outside of the oVirt environment, so not all orphaned disks on the existing storage domain will be artifacts of supposedly-deleted data. For our use case, disk images created by us will be able to be imported into oVirt and attached to a VM created through the engine. Because of this, saying "if it isn't in the engine db, it's not ours" wouldn't necessarily be true.
When you talk about checking the metadata, does either oVirt or vdsm have a simple way to do this? A query of some sort would be ideal for this, as it could be run for each image as a qualifier for import.
Also, as far as writing the functionality itself, I'm gathering that it should be structured as a query to return these orphaned images, which can then be acted upon/added to the database through a separate command after checking the validity of each image?
>> [1] or a subtab on the storage domain. >> >> _______________________________________________ >> Engine-devel mailing list >> Engine-devel@ovirt.org >> http://lists.ovirt.org/mailman/listinfo/engine-devel >> --
Regards,
Dan Yasny Red Hat Israel +972 9769 2280
--
Regards,
Dan Yasny Red Hat Israel +972 9769 2280
--
Regards,
Dan Yasny Red Hat Israel +972 9769 2280
Engine-devel mailing list Engine-devel@ovirt.org http://lists.ovirt.org/mailman/listinfo/engine-devel
-- Shu Ming <shuming@linux.vnet.ibm.com> IBM China Systems and Technology Laboratory
On 08/02/2012 04:44 AM, Shu Ming wrote:
No comments below. I am just curious how you can have disk created outside of the oVirt environment if the storage domain is mounted on oVirt engine. Does your application try to communicate with VDSM though SPM host to do that? Are the two applications(oVirt engine and your application) coexisting and manipulating the storage domain at the same time or one application is quiet when the other one is functioning? IMHO, modifying the storage domain meta data from two application are dangerous and I suppose your application should know the reason and what these disks are for. So telling oVirt to import the disks automatically should be reasonable because you know what these disks are for and it is unnecessary for the oVirt administrator to select which one to import.
two use cases: 1. NFS storage allows this quite easily, and very relevant with storage side cloning. 2. engine and storage go out of sync (recover either from backup)
On 2012-8-2 1:36, Hopper, Ricky wrote:
On 8/1/12 10:05 AM, "Dan Yasny" <dyasny@redhat.com> wrote:
From: "Ricky Hopper" <Ricky.Hopper@netapp.com> To: "Dan Yasny" <dyasny@redhat.com> Cc: engine-devel@ovirt.org, "Itamar Heim" <iheim@redhat.com>, "Andrew Cathrow" <acathrow@redhat.com> Sent: Wednesday, 1 August, 2012 4:56:45 PM Subject: Re: [Engine-devel] Domain rescan action question
On 8/1/12 9:42 AM, "Dan Yasny" <dyasny@redhat.com> wrote:
----- Original Message -----
From: "Ricky Hopper" <Ricky.Hopper@netapp.com> To: "Dan Yasny" <dyasny@redhat.com>, "Andrew Cathrow" <acathrow@redhat.com> Cc: engine-devel@ovirt.org, "Itamar Heim" <iheim@redhat.com>, "Ricky Hopper" <Ricky.Hopper@netapp.com> Sent: Wednesday, 1 August, 2012 4:34:53 PM Subject: Re: [Engine-devel] Domain rescan action question
On 8/1/12 5:59 AM, "Dan Yasny" <dyasny@redhat.com> wrote:
> > ----- Original Message ----- >> From: "Andrew Cathrow" <acathrow@redhat.com> >> To: "Itamar Heim" <iheim@redhat.com>, "Dan Yasny" >> <dyasny@redhat.com>, >> "Ricky Hopper" <Ricky.Hopper@netapp.com> >> Cc: engine-devel@ovirt.org >> Sent: Wednesday, 1 August, 2012 12:24:42 AM >> Subject: Re: [Engine-devel] Domain rescan action question >> >> >> >> ----- Original Message ----- >>> From: "Itamar Heim" <iheim@redhat.com> >>> To: "Ricky Hopper" <Ricky.Hopper@netapp.com> >>> Cc: engine-devel@ovirt.org >>> Sent: Tuesday, July 31, 2012 4:44:34 PM >>> Subject: Re: [Engine-devel] Domain rescan action question >>> >>> On 07/31/2012 11:30 PM, Hopper, Ricky wrote: >>>> Hey all, >>>> >>>> As I'm making progress with the domain rescan >>>> functionality, >>>> I've >>>> realized that I'm unsure what to do with any disks that are >>>> detected on >>>> the domain. Should I add them back into the database to be >>>> listed >>>> as >>>> floating disks, or should I just return a list of disk >>>> images >>>> to >>>> be >>>> attached to whatever the caller of the query needs? >>>> >>>> - Ricky >>> i'm not sure they should be added automatically. >>> I think a dialog[1] showing orphan disks/images on the >>> storage >>> domain >>> for user to choose which to import as 'floating' disks would >>> be >>> better >>> than auto importing them. >>> >>> there is also the reverse of flagging existing disks as >>> 'missing' >>> in >>> storage? >>> >> Perhaps we should start a feature page to discuss and better >> scope >> it. >> There is a feature page that we could expand, it doesn't >> discuss >> the >> notion of importing those disks which is certainly something we >> need >> to address. >> >> >> http://wiki.ovirt.org/wiki/Features/Orphaned_Images > The original idea was to scan the storage domains and compare the > images > lists to the database, thus getting a list of images no longer > relevant > and scrubbing the storage. This will actually be addressed > properly > in > the future (Ayal can elaborate on that) but for now this is > needed > at > least for that use case. > > > As I understand, the conversation here is about trying to take an > already > populated SD (from another setup I suppose), scanning it and > putting > it > into RHEV? As I understood it, the purpose of this functionality wasn't to find images which should be removed from storage, but to find images on the domain that oVirt was unaware of and importing them for use (for instance, if a disk was created outside of oVirt on the domain). If one of the use cases for this feature is also the orphaned images mentioned on the feature page, that may expand the functionality into a separate domain scrub and storage import, both of which would call the rescan (meaning the rescan would not actually add to the database, but instead return a list of "orphaned" disk images).
Another solution would be to import all disk images into the database either way, and let the user delete any orphaned images from the GUI. I think are nice to have, but the problem with the scanning is that if we're not scanning a master domain or an export domain, all we will see is a bunch of images with no context or even hints as to where they belong. The data that makes it all usable is in the engine database and in the ovf files on the master domain.
This is why I stopped at the orphaned images part of the feature - because there it's feasible, I would rely on the engine database for image ID comparisons.
If we present a user with a list of nameless disks, I doubt it will be of any use.
The way this would work is by comparing a list of disk images from vdsm and from oVirt's database, finding the ones vdsm returns that oVirt doesn't have, and then either adding or returning those images. So oVirt's db will be used in the comparison. This will work only when scanning storage domains already attached and in use by the current oVirt setup. What I am talking about is what will happen if a LUN that used to be a SD in another oVirt setup is discovered and scanned, with no engine db to compare with. If we don't consider such a use case, life is definitely quite easy, and we're basically within
----- Original Message ----- the scope of the orphaned images feature
This use case should definitely be considered, maybe have a separate case where the rescan would return all "compatible" disks (i.e. disks that aren't just partial snapshots and the like) if the domain has not yet been mounted. Essentially, it would run the same comparison, but compare against an empty list rather than a list of disks. There's no way it's as simple as that (I'm unsure of the methods oVirt uses to mount a domain), but it's a good starting point.
As far as presenting the user with nameless disks, that's a point I hadn't considered; we could generate some sort of placeholder metadata upon addition to show the user that these are new/orphaned disks that were found on the storage domain. Is it safe to assume that the disks discovered by this feature won't be attached to anything? The oVirt paradigm says "if it isn't in the engine db, it's not ours", so any LV or image we discover that is missing from the DB or the snapshot chain of the image in the DB, is nameless, and orphaned.
Such an image on a current SD, belonging to a working oVirt setup is definitely an orphaned image. Attaching these to VMs is usually also useless, because they are more often than not discarded snapshots that didn't get discarded cleanly for some reason.
Now, if we want to make this usable, we might want to actually check the qcow2 metadata of the image to see whether it's a mid-chain snapshot (and if so it's probably just a candidate for cleanup), or a standalone qcow2 or raw image, and then we can move on with the virt-* tools, to find out the image size and the filesystems it contains. This will at least provide the user with some usable information about the detected image. If we're talking about scanning an SD that doesn't presently belong to the current oVirt setup, then this is even more relevant, because all of the images will have no VM-related context. We're currently working on having disks created outside of the oVirt environment, so not all orphaned disks on the existing storage domain will be artifacts of supposedly-deleted data. For our use case, disk images created by us will be able to be imported into oVirt and attached to a VM created through the engine. Because of this, saying "if it isn't in the engine db, it's not ours" wouldn't necessarily be true.
When you talk about checking the metadata, does either oVirt or vdsm have a simple way to do this? A query of some sort would be ideal for this, as it could be run for each image as a qualifier for import.
Also, as far as writing the functionality itself, I'm gathering that it should be structured as a query to return these orphaned images, which can then be acted upon/added to the database through a separate command after checking the validity of each image?
>>> [1] or a subtab on the storage domain. >>> >>> _______________________________________________ >>> Engine-devel mailing list >>> Engine-devel@ovirt.org >>> http://lists.ovirt.org/mailman/listinfo/engine-devel >>> > -- > > > > Regards, > > Dan Yasny > Red Hat Israel > +972 9769 2280
--
Regards,
Dan Yasny Red Hat Israel +972 9769 2280
--
Regards,
Dan Yasny Red Hat Israel +972 9769 2280
Engine-devel mailing list Engine-devel@ovirt.org http://lists.ovirt.org/mailman/listinfo/engine-devel
participants (7)
-
Andrew Cathrow -
Ayal Baron -
Dan Yasny -
Hopper, Ricky -
Itamar Heim -
Omer Frenkel -
Shu Ming