Hi all, As part of adding Gluster support in ovirt, we need to introduce some Storage Device management capabilities (on the host). Since these are quite generic and not specific to Gluster as such, we think it might be useful to add it as a core vdsm and oVirt feature. At a high level, this involves following: - A "Storage Devices" sub-tab on "Host" entity, displaying information about all the storage devices* - Listing of different types of storage devices of a host - Regular Disks and Partitions* - LVM* - Software RAID* - Various actions related to device configuration - Partition disks* - Format and mount disks / partitions* - Create, resize and delete LVM Volume Groups (VGs) - Create, resize, delete, format and mount LVM Logical Volumes (LVs) - Create, resize, delete, partition, format and mount Software RAID devices - Edit properties of the devices - UI can be modeled similar to the system-config-lvm tool The items marked with (*) in above list are urgently required for the Gluster feature, and will be developed first. Comments / inputs welcome. Thanks, Shireesh _______________________________________________ Arch mailing list Arch(a)ovirt.org http://lists.ovirt.org/mailman/listinfo/arch

On Tue, Apr 17, 2012 at 03:38:25PM +0530, Shireesh Anjal wrote: > Hi all, > > As part of adding Gluster support in ovirt, we need to introduce > some Storage Device management capabilities (on the host). Since > these are quite generic and not specific to Gluster as such, we > think it might be useful to add it as a core vdsm and oVirt > feature. > At a high level, this involves following: > > - A "Storage Devices" sub-tab on "Host" entity, displaying > information about all the storage devices* > - Listing of different types of storage devices of a host > - Regular Disks and Partitions* > - LVM* > - Software RAID* > - Various actions related to device configuration > - Partition disks* > - Format and mount disks / partitions* > - Create, resize and delete LVM Volume Groups (VGs) > - Create, resize, delete, format and mount LVM Logical Volumes > (LVs) > - Create, resize, delete, partition, format and mount Software > RAID devices > - Edit properties of the devices > - UI can be modeled similar to the system-config-lvm tool > > The items marked with (*) in above list are urgently required for > the Gluster feature, and will be developed first. > > Comments / inputs welcome. This seems like a big undertaking, and I would like to understand the complete use case of this. Is it intended to create the block storage devices on top of which a Gluster volume will be created?

I must tell that we had a bad experience with exposing low level commands over the Vdsm API: A Vdsm storage domain is a VG with some metadata on top. We used to have two API calls for creating a storage domain: one to create the VG and one to add the metadata and make it an SD. But it is pretty hard to handle all the error cases remotely. It proved more useful to have one atomic command for the whole sequence. I suspect that this would be the case here, too. I'm not sure if using Vdsm as an ssh-replacement for transporting lvm/md/fdisk commands is the best approach.

It may be better to have a single verb for creating Gluster volume out of block storage devices. Something like: "take these disks, partition them, build a raid, cover with a vg, carve some PVs and make each of them a Gluster volume". Obviously, it is not simple to define a good language to describe a general architecture of a Gluster voluem. But it would have to be done somewhere - if not in Vdsm then in Engine; and I suspect it would be better done on the local host, not beyond a fragile network link. Please note that currently, Vdsm makes a lot of effort not to touch LVM metadata of existing VGs on regular "HSM" hosts. All such operations are done on the engine-selected "SPM" host. When implementing this, we must bear in mind these safeguards and think whether we want to break them.

Regards, Dan. _______________________________________________ Arch mailing list Arch(a)ovirt.org http://lists.ovirt.org/mailman/listinfo/arch

On Wed, Apr 18, 2012 at 09:06:36AM -0400, Ayal Baron wrote: > > > ----- Original Message ----- > > On Tue, Apr 17, 2012 at 03:38:25PM +0530, Shireesh Anjal wrote: > > > Hi all, > > > > > > As part of adding Gluster support in ovirt, we need to > > > introduce > > > some Storage Device management capabilities (on the host). > > > Since > > > these are quite generic and not specific to Gluster as such, we > > > think it might be useful to add it as a core vdsm and oVirt > > > feature. > > > At a high level, this involves following: > > > > > > - A "Storage Devices" sub-tab on "Host" entity, displaying > > > information about all the storage devices* > > > - Listing of different types of storage devices of a host > > > - Regular Disks and Partitions* > > > - LVM* > > > - Software RAID* > > > - Various actions related to device configuration > > > - Partition disks* > > > - Format and mount disks / partitions* > > > - Create, resize and delete LVM Volume Groups (VGs) > > > - Create, resize, delete, format and mount LVM Logical > > > Volumes > > > (LVs) > > > - Create, resize, delete, partition, format and mount > > > Software > > > RAID devices > > > - Edit properties of the devices > > > - UI can be modeled similar to the system-config-lvm tool > > > > > > The items marked with (*) in above list are urgently required > > > for > > > the Gluster feature, and will be developed first. > > > > > > Comments / inputs welcome. > > > > This seems like a big undertaking, and I would like to understand > > the > > complete use case of this. Is it intended to create the block > > storage > > devices on top of which a Gluster volume will be created? > > Yes, but not only. > It could also be used to create the file system on top of which you > create a local storage domain (just an example, there are many > others, more listed below). > > > > > I must tell that we had a bad experience with exposing low level > > commands over the Vdsm API: A Vdsm storage domain is a VG with > > some > > metadata on top. We used to have two API calls for creating a > > storage > > domain: one to create the VG and one to add the metadata and make > > it > > an > > SD. But it is pretty hard to handle all the error cases remotely. > > It > > proved more useful to have one atomic command for the whole > > sequence. > > > > I suspect that this would be the case here, too. I'm not sure if > > using > > Vdsm as an ssh-replacement for transporting lvm/md/fdisk commands > > is > > the > > best approach. > > I agree, we should either provide added value or figure out a way > where we don't need to simply add a verb every time the underlying > APIs added something. > > > > > It may be better to have a single verb for creating Gluster > > volume > > out > > of block storage devices. Something like: "take these disks, > > partition > > them, build a raid, cover with a vg, carve some PVs and make each > > of > > them a Gluster volume". > > > > Obviously, it is not simple to define a good language to describe > > a > > general architecture of a Gluster voluem. But it would have to be > > done > > somewhere - if not in Vdsm then in Engine; and I suspect it would > > be > > better done on the local host, not beyond a fragile network link. > > > > Please note that currently, Vdsm makes a lot of effort not to > > touch > > LVM > > metadata of existing VGs on regular "HSM" hosts. All such > > operations > > are > > done on the engine-selected "SPM" host. When implementing this, > > we > > must > > bear in mind these safeguards and think whether we want to break > > them. > > I'm not sure I see how this is relevant, we allow creating a VG on > any host today and that isn't going to change... We have one painful exception, that alone is no reason to add more. Note that currently, Engine uses the would-be-spm for vg creation. In the gluster use case, any host is expected to do this on async timing. It might be required, but it's not warm and fuzzy.

> > In general, we know that we already need to support using a LUN > even if it has partitions on it (with force or something). > > We know that we have requirements for more control over the VG that > we create e.g. support striping, control over max LV size (limited > by pv extent size today) etc. > > We also know that users would like a way not only to use a local > dir for a storage domain but also create the directory + fs? These three examples are storage domain flavors..

> > We know that in the gLuster use case we would like the ability to > setup samba over the gluster volume as well as iSCSI probably. Now I do not see the relevance. Configuring gluster and how it exposes its volume is something other than preparing block storage for gluster bricks.

> > So although I believe that when we create a gluster volume or an > ovirt storage domain then indeed we shouldn't need a lot of low > level commands, but it would appear to me that not allowing for > more control when needed is not going to work and that there are > enough use cases which do not involve a gluster volume nor a > storage domain to warrant this to be generic. I'm not against more control; I'm against uncontrollable API such as runThisLvmCommandAsRoot()

>>> So although I believe that when we create a gluster volume or an >>> ovirt storage domain then indeed we shouldn't need a lot of low >>> level commands, but it would appear to me that not allowing for >>> more control when needed is not going to work and that there are >>> enough use cases which do not involve a gluster volume nor a >>> storage domain to warrant this to be generic. >> I'm not against more control; I'm against uncontrollable API such as >> runThisLvmCommandAsRoot() > I can't argue with this. > I think what we're missing here though is something similar to > setupNetworks which would solve the problem. Not have 100 verbs > (createPartition, createFS, createVG, createLV, setupRaid,...) but > rather have setupStorage (better name suggestions are welcome) which > would get the list of objects to use and the final configuration to > setup. > > This way we'd have a 2 stage process: > 1. setupStorage (generic) I was looking up on the VDSM archives and there are talks of using libstoragemgmt (lsm) under VDSM. I was wondering if the setupStorage would be something where lsm would be used to do the work, it seems fit for purpose here.

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>> This way we'd have a 2 stage process: >> 1. setupStorage (generic) > I was looking up on the VDSM archives and there are talks of using > libstoragemgmt (lsm) Funny, we started using that acronym for Live Storage Migration :) > under VDSM. I was wondering if the setupStorage would be something > where > lsm would > be used to do the work, it seems fit for purpose here. > > I don't think this is the libstoragemgmt mandate. libstoragemgmt is: "A library that will provide a vendor agnostic open source storage application programming interface (API) for storage arrays." i.e. it is there to abstract storage array specifics from the user. It will be used by things like LVM etc, not the other way around. setupStorage would use libstoragemgmt wherever appropriate of course. But as the libstoragemgmt maintainer, Tony (cc'd) can correct me if I'm wrong here.

----- Original Message ----- > On 04/22/2012 12:28 PM, Ayal Baron wrote: >>>> This way we'd have a 2 stage process: >>>> 1. setupStorage (generic) >>> I was looking up on the VDSM archives and there are talks of using >>> libstoragemgmt (lsm) >> Funny, we started using that acronym for Live Storage Migration :) >> >>> under VDSM. I was wondering if the setupStorage would be something >>> where >>> lsm would >>> be used to do the work, it seems fit for purpose here. >>> >>> >> I don't think this is the libstoragemgmt mandate. >> >> libstoragemgmt is: >> "A library that will provide a vendor agnostic open source storage >> application programming interface (API) for storage arrays." >> >> i.e. it is there to abstract storage array specifics from the user. >> It will be used by things like LVM etc, not the other way around. >> >> setupStorage would use libstoragemgmt wherever appropriate of >> course. >> >> But as the libstoragemgmt maintainer, Tony (cc'd) can correct me if >> I'm wrong here. >> >> > I was looking at setupStorage as Provisioning + Setting up. > I know one of the basic goals of lsm is provision the storage to the > host > and preparing the storage for consumption is higher layers work. > > With that, i think then its becomes a 3 stage process, from > oVirt/VDSM > pov... > 1) Provision Storage (using lsm if applicable, based on whether > external > storage is connected) > 2) Setup Storage (prepare the provisioned LUNs for usage) > 3) createSD/createGlusterVolume/... (plugin specific) > > Since we are talking about Storage management using VDSM, i was > interested in understanding the plans, strategy of how VDSM + lsm > will integrate ? There are various ways of approaching this. 1. Given proper storage you could just provision new LUNs whenever you need a new virtual disk and utilize storage side thin provisioning and snapshots for most of your needs. When you have such storage you don't really need steps 2 and 3 above. Your storage is your virtual images repository. Although quite simple and powerful, very few arrays are capable of growing to a very large number of objects (luns + snapshots + whatever) today, so I don't see this being the most common use case any time soon.

2. Provision LUNs (either statically or dynamically using lsm) once, preferably thinly provisioned. Then setupStorage (storage domain over VG / gLuster / other) and use lsm for creating snapshots/clones on the fly In my opinion this will be more prevalent to begin with. With lsm we will (hopefully) have a way of enumerating storage side capabilities so then when we create a repository (gluster / sd / ...) we'd be able to determine on the fly what capabilities it has and determine if to use these or to use virtualized capabilities (e.g. in the virt case when you need to create a snapshot use qcowX). In oVirt, once you've defined a storage domain and it exposes a set of capabilities, user should be able to override (e.g. even though storage supports snapshots, I want to use qcow as this storage can only create 255 snapshots per volume and I need more than that). I'm assuming that we will not have any way of knowing the limits per machine. Does that make sense?

----- Original Message ----- > On 04/24/2012 02:07 AM, Ayal Baron wrote: >> ----- Original Message ----- >>> On 04/22/2012 12:28 PM, Ayal Baron wrote: >>>>>> This way we'd have a 2 stage process: >>>>>> 1. setupStorage (generic) >>>>> I was looking up on the VDSM archives and there are talks of >>>>> using >>>>> libstoragemgmt (lsm) >>>> Funny, we started using that acronym for Live Storage Migration >>>> :) >>>> >>>>> under VDSM. I was wondering if the setupStorage would be >>>>> something >>>>> where >>>>> lsm would >>>>> be used to do the work, it seems fit for purpose here. >>>>> >>>>> >>>> I don't think this is the libstoragemgmt mandate. >>>> >>>> libstoragemgmt is: >>>> "A library that will provide a vendor agnostic open source >>>> storage >>>> application programming interface (API) for storage arrays." >>>> >>>> i.e. it is there to abstract storage array specifics from the >>>> user. >>>> It will be used by things like LVM etc, not the other way around. >>>> >>>> setupStorage would use libstoragemgmt wherever appropriate of >>>> course. >>>> >>>> But as the libstoragemgmt maintainer, Tony (cc'd) can correct me >>>> if >>>> I'm wrong here. >>>> >>>> >>> I was looking at setupStorage as Provisioning + Setting up. >>> I know one of the basic goals of lsm is provision the storage to >>> the >>> host >>> and preparing the storage for consumption is higher layers work. >>> >>> With that, i think then its becomes a 3 stage process, from >>> oVirt/VDSM >>> pov... >>> 1) Provision Storage (using lsm if applicable, based on whether >>> external >>> storage is connected) >>> 2) Setup Storage (prepare the provisioned LUNs for usage) >>> 3) createSD/createGlusterVolume/... (plugin specific) >>> >>> Since we are talking about Storage management using VDSM, i was >>> interested in understanding the plans, strategy of how VDSM + lsm >>> will integrate ? >> There are various ways of approaching this. >> 1. Given proper storage you could just provision new LUNs whenever >> you need a new virtual disk and utilize storage side thin >> provisioning and snapshots for most of your needs. >> When you have such storage you don't really need steps 2 and 3 >> above. Your storage is your virtual images repository. >> Although quite simple and powerful, very few arrays are capable of >> growing to a very large number of objects (luns + snapshots + >> whatever) today, so I don't see this being the most common use >> case any time soon. > This is not clear to me. This only talks about provisioning but not > consuming. > 2 and 3 above are required from a consumability perspective. The LUNs > will have > to prepared and used by LVM (pv, vg, lv, metadata) for VDSM to host a > storage domain. There are several ways of managing the repo in such a scenario, just an example is to provision a LUN where vdsm would manage metadata (listing of images, relations between snapshots, logical sizes of images, etc) and every image is another LUN that we would provision, so there would be no need for LVM in such a scenario.

> >> 2. Provision LUNs (either statically or dynamically using lsm) >> once, preferably thinly provisioned. Then setupStorage (storage >> domain over VG / gLuster / other) and use lsm for creating >> snapshots/clones on the fly >> In my opinion this will be more prevalent to begin with. >> >> With lsm we will (hopefully) have a way of enumerating storage side >> capabilities so then when we create a repository (gluster / sd / >> ...) we'd be able to determine on the fly what capabilities it has >> and determine if to use these or to use virtualized capabilities >> (e.g. in the virt case when you need to create a snapshot use >> qcowX). >> >> In oVirt, once you've defined a storage domain and it exposes a set >> of capabilities, user should be able to override (e.g. even though >> storage supports snapshots, I want to use qcow as this storage can >> only create 255 snapshots per volume and I need more than that). >> >> I'm assuming that we will not have any way of knowing the limits >> per machine. >> >> Does that make sense? >> > Agree to #2. Thinking deeper.... > > 1) Provisioning Storage > > Provisioning storage using lsm would require new VDSM verbs to be > added, > which can create / show the LUNs to the oVirt user and user can then > select which LUN(s) to use for setupStorage. create LUN doesn't exist today, but show LUNs does. Currently the (simplified) flow is: 1. connect to storage (when relevant) 2. get listing of devices 3. create a storage domain on selected devices > Provisioning LUNs will probably exploit the lsm capabilities and > provide > the options to the user to create the LUNs using the available array > features. > > With GlusterFS also providing some of the array capabilities (stripe, > replicate etc), user might want to provision GlusterFS volume (with > whatever capabilities gluster offers) to host storage upon, > especially > if the storage is coming from not-so-reliable commodity hw storage. > > I feel this also has to be considered as part of provisioning and > should > come before the setupStorage step. > > IMHO, there should be a "Storage Provisioning" tab in oVirt which > will > allow user to ... > > 1a) Carve LUNs from external Storage array. > > 1b) Provision storage as GlusterFS volume. User can select the > LUNs > carved (from #1a) as bricks for GlusterFS volume, if need be. > > 1c) Use local host free disk space. > > Somewhere here there should be option ( as applicable) for user to > select whether to exploit storage array features or host virt > capabilities for say snapshot, in cases where both are applicable. > > 2) Setup Storage > > Here the user would create VDSM file or block based storage domain, > based on the storage provisioned from the "Storage Provisioning" tab. > I believe this is where VDSM will add its metadata to the > provisioned > storage to make it a storage domain. > > IMHO for image operations like snapshot/clone, VDSM will have to > track& > maintain whether the image is served by local host, external storage > array or gluster volume and accordingly use the lvm, lsm or gluster > apis > to get the job done. For sure. That would be part of the domain metadata. > 3) Not sure if anymore steps needed ? In general I agree with the above. wrt the scope of setupStorage, it's semantics. Personally I think we should differentiate between provisioning storage on the target side and provisioning on the initiator side. The flow (from GUI) as I see it is (with lsm and an array that supports dynamic provisioning): 1. provide credentials and login into storage (out of band, using lsm) 2. enumerate capabilities 3. based on 2, define required storage domain characteristics (size, thin provisioning, etc) - but note that this is generic, so should apply to gluster as well 4. create a storage domain - would implicitly create 1 or more LUNs and anything else that is needed according to above specifications. API wise, this is probably 3 calls, 1. provision LUNs, 2. setupStorage and 3. createStorageDomain/createGlusterVolume/... Characteristics might include things like partitions, encryption?, compression?, raid, file systems, etc.

On 04/24/2012 07:37 PM, Ayal Baron wrote: > > ----- Original Message ----- >> On 04/24/2012 02:07 AM, Ayal Baron wrote: >>> ----- Original Message ----- >>>> On 04/22/2012 12:28 PM, Ayal Baron wrote: >>>>>>> This way we'd have a 2 stage process: >>>>>>> 1. setupStorage (generic) >>>>>> I was looking up on the VDSM archives and there are talks of >>>>>> using >>>>>> libstoragemgmt (lsm) >>>>> Funny, we started using that acronym for Live Storage Migration >>>>> :) >>>>> >>>>>> under VDSM. I was wondering if the setupStorage would be >>>>>> something >>>>>> where >>>>>> lsm would >>>>>> be used to do the work, it seems fit for purpose here. >>>>>> >>>>>> >>>>> I don't think this is the libstoragemgmt mandate. >>>>> >>>>> libstoragemgmt is: >>>>> "A library that will provide a vendor agnostic open source >>>>> storage >>>>> application programming interface (API) for storage arrays." >>>>> >>>>> i.e. it is there to abstract storage array specifics from the >>>>> user. >>>>> It will be used by things like LVM etc, not the other way >>>>> around. >>>>> >>>>> setupStorage would use libstoragemgmt wherever appropriate of >>>>> course. >>>>> >>>>> But as the libstoragemgmt maintainer, Tony (cc'd) can correct >>>>> me >>>>> if >>>>> I'm wrong here. >>>>> >>>>> >>>> I was looking at setupStorage as Provisioning + Setting up. >>>> I know one of the basic goals of lsm is provision the storage to >>>> the >>>> host >>>> and preparing the storage for consumption is higher layers work. >>>> >>>> With that, i think then its becomes a 3 stage process, from >>>> oVirt/VDSM >>>> pov... >>>> 1) Provision Storage (using lsm if applicable, based on whether >>>> external >>>> storage is connected) >>>> 2) Setup Storage (prepare the provisioned LUNs for usage) >>>> 3) createSD/createGlusterVolume/... (plugin specific) >>>> >>>> Since we are talking about Storage management using VDSM, i was >>>> interested in understanding the plans, strategy of how VDSM + >>>> lsm >>>> will integrate ? >>> There are various ways of approaching this. >>> 1. Given proper storage you could just provision new LUNs >>> whenever >>> you need a new virtual disk and utilize storage side thin >>> provisioning and snapshots for most of your needs. >>> When you have such storage you don't really need steps 2 and 3 >>> above. Your storage is your virtual images repository. >>> Although quite simple and powerful, very few arrays are capable >>> of >>> growing to a very large number of objects (luns + snapshots + >>> whatever) today, so I don't see this being the most common use >>> case any time soon. >> This is not clear to me. This only talks about provisioning but >> not >> consuming. >> 2 and 3 above are required from a consumability perspective. The >> LUNs >> will have >> to prepared and used by LVM (pv, vg, lv, metadata) for VDSM to >> host a >> storage domain. > There are several ways of managing the repo in such a scenario, > just an example is to provision a LUN where vdsm would manage > metadata (listing of images, relations between snapshots, logical > sizes of images, etc) and every image is another LUN that we would > provision, so there would be no need for LVM in such a scenario. > Sorry, but not clear to me. If vdsm is configured for file based storage domain, it would expect the LUN to have a fs, and vdsm would create the fs storage domain over it. If vdsm is configured for block based storage domain, it would end up using the LUN as a pv, over which the VG/LV would sit (hence the need for lvm) and form the block storage domain, unless you are talking of vdsm using raw LUNs which is not supported today ?

>> >>> 2. Provision LUNs (either statically or dynamically using lsm) >>> once, preferably thinly provisioned. Then setupStorage (storage >>> domain over VG / gLuster / other) and use lsm for creating >>> snapshots/clones on the fly >>> In my opinion this will be more prevalent to begin with. >>> >>> With lsm we will (hopefully) have a way of enumerating storage >>> side >>> capabilities so then when we create a repository (gluster / sd / >>> ...) we'd be able to determine on the fly what capabilities it >>> has >>> and determine if to use these or to use virtualized capabilities >>> (e.g. in the virt case when you need to create a snapshot use >>> qcowX). >>> >>> In oVirt, once you've defined a storage domain and it exposes a >>> set >>> of capabilities, user should be able to override (e.g. even >>> though >>> storage supports snapshots, I want to use qcow as this storage >>> can >>> only create 255 snapshots per volume and I need more than that). >>> >>> I'm assuming that we will not have any way of knowing the limits >>> per machine. >>> >>> Does that make sense? >>> >> Agree to #2. Thinking deeper.... >> >> 1) Provisioning Storage >> >> Provisioning storage using lsm would require new VDSM verbs to be >> added, >> which can create / show the LUNs to the oVirt user and user can >> then >> select which LUN(s) to use for setupStorage. > create LUN doesn't exist today, but show LUNs does. > > Currently the (simplified) flow is: > 1. connect to storage (when relevant) > 2. get listing of devices > 3. create a storage domain on selected devices > >> Provisioning LUNs will probably exploit the lsm capabilities and >> provide >> the options to the user to create the LUNs using the available >> array >> features. >> >> With GlusterFS also providing some of the array capabilities >> (stripe, >> replicate etc), user might want to provision GlusterFS volume >> (with >> whatever capabilities gluster offers) to host storage upon, >> especially >> if the storage is coming from not-so-reliable commodity hw >> storage. >> >> I feel this also has to be considered as part of provisioning and >> should >> come before the setupStorage step. >> >> IMHO, there should be a "Storage Provisioning" tab in oVirt which >> will >> allow user to ... >> >> 1a) Carve LUNs from external Storage array. >> >> 1b) Provision storage as GlusterFS volume. User can select >> the >> LUNs >> carved (from #1a) as bricks for GlusterFS volume, if need be. >> >> 1c) Use local host free disk space. >> >> Somewhere here there should be option ( as applicable) for user to >> select whether to exploit storage array features or host virt >> capabilities for say snapshot, in cases where both are applicable. >> >> 2) Setup Storage >> >> Here the user would create VDSM file or block based storage >> domain, >> based on the storage provisioned from the "Storage Provisioning" >> tab. >> I believe this is where VDSM will add its metadata to the >> provisioned >> storage to make it a storage domain. >> >> IMHO for image operations like snapshot/clone, VDSM will have to >> track& >> maintain whether the image is served by local host, external >> storage >> array or gluster volume and accordingly use the lvm, lsm or >> gluster >> apis >> to get the job done. > For sure. That would be part of the domain metadata. > >> 3) Not sure if anymore steps needed ? > In general I agree with the above. wrt the scope of setupStorage, > it's semantics. Personally I think we should differentiate > between provisioning storage on the target side and provisioning > on the initiator side. > > The flow (from GUI) as I see it is (with lsm and an array that > supports dynamic provisioning): > 1. provide credentials and login into storage (out of band, using > lsm) > 2. enumerate capabilities > 3. based on 2, define required storage domain characteristics > (size, thin provisioning, etc) > - but note that this is generic, so should apply to gluster as > well > 4. create a storage domain - would implicitly create 1 or more LUNs > and anything else that is needed according to above > specifications. API wise, this is probably 3 calls, 1. provision > LUNs, 2. setupStorage and 3. > createStorageDomain/createGlusterVolume/... > > Characteristics might include things like partitions, encryption?, > compression?, raid, file systems, etc. > This seems interesting. I am interested in pursuing this further and helping contribute to the vdsm lsm integration. lsm is still in the early stages, but i feel its the right time to start influencing it so that vdsm integration can be smooth. My interest mainly lies in how external storage array can be integrated into oVirt/VDSM and help oVirt exploit the array offload features as part of the virtualization stack. I didn't find any oVirt wiki page on this topic, tho' there is a old mailing list thread on vdsm lsm integration, which when read brings up more issues to discuss :) How does storage repo engine and possible vdsm services framework ( i learnt about these in my brief chat with Saggie some time back) play a role here ?

Can "Provisioning Storage" itself be like a high level service, with gluster and lsm exposing storage services, which vdsm can enumerate and send to oVirt GUI, is that the idea ?

Is there any wiki page on this topic which lists the todos on this front, which I can start looking at ?

thanx, deepak

>> This seems interesting. >> >> I am interested in pursuing this further and helping contribute to >> the >> vdsm lsm integration. lsm is still in the early stages, but i feel >> its >> the right time to start influencing it so that vdsm integration >> can >> be >> smooth. My interest mainly lies in how external storage array can >> be >> integrated into oVirt/VDSM and help oVirt exploit the array >> offload >> features as part of the virtualization stack. >> >> I didn't find any oVirt wiki page on this topic, tho' there is a >> old >> mailing list thread on vdsm lsm integration, which when read >> brings >> up >> more issues to discuss :) >> How does storage repo engine and possible vdsm services framework >> ( i >> learnt about these in my brief chat with Saggie some time back) >> play >> a >> role here ? > Maybe Saggi could elaborate here. > >> Can "Provisioning Storage" itself be like a high level service, >> with >> gluster and lsm exposing storage services, which vdsm can >> enumerate >> and >> send to oVirt GUI, is that the idea ? > I'm not sure "Provisioning Storage" is a clear enough definition, > as it could cover a lot of possibly unrelated things, but I'd need > to understand more what you mean to really be able to comment > properly. > Well, I was envisioning oVirt as being able to provision and consume storage, both, going ahead. Provisioning thru' vdsm-libstoragemgmt (lsm) integration. oVirt user should be able to carve out LUNs, be able to associate the LUNs visibility to host(s) of a oVirt cluster, all via libstoragemgmt interfaces. With gluster being integrated into vdsm, oVirt user can provision and manage gluster volumes soon, which also falls under "provisioning storage", hence I was wondering if there would be a new tab in oVirt for "provisioning storage", where gluster ( in near future) and external array/LUNs ( via vdsm -lsm integration) can be provisioned.

>> Is there any wiki page on this topic which lists the todos on this >> front, which I can start looking at ? > Unfortunately there is not as we haven't sat down to plan it in > depth, but you're more than welcome to start it. > > Generally, the idea is as follows: > Currently vdsm has storage virtualization capabilites, i.e. we've > implemented a form of thin-provisioning, we provide snapshots > using qcow etc, without relying on the hardware. Using lsm we > could have feature negotiation and whenever we can offload, do it. > e.g. we could know if a storage array supports thin cloning, if it > supports thick cloning, if a LUN supports thin provisioning etc. > In the last example (thin provisioning) when we create a VG on top > of a thin-p LUN we should create all disk image (LVs) > 'preallocated' and avoid vdsm's thin provisioning implementation > (as it is not needed). > I was thinking libstoragemgmt 'query capability' or similar interface should help vdsm know the array capabilities.

I agree that if the backing LUN already is thinp'ed, then vdsm should not add its own over it. So such usecases & needs from vdsm perspective need to be thought about and eventually it should influence the libstoragemgmt interfaces

> However, we'd need a mechanism at domain level to 'disable' some of > the capabilities, so for example if we know that on a specific > array snapshots are limited or provide poor performance (worse > than qcow) or whatever, we'd be able to fall back to vdsm's > software implementation. > I was thinking that its for the user to decide, not sure if we can auto-detect and automate this. But i feel this falls under the 'advanced usecase' category :) We can always think about this later, rite ?

Hi all, As part of adding Gluster support in ovirt, we need to introduce some Storage Device management capabilities (on the host). Since these are quite generic and not specific to Gluster as such, we think it might be useful to add it as a core vdsm and oVirt feature. At a high level, this involves following: - A "Storage Devices" sub-tab on "Host" entity, displaying information about all the storage devices* - Listing of different types of storage devices of a host - Regular Disks and Partitions* - LVM* - Software RAID* - Various actions related to device configuration - Partition disks* - Format and mount disks / partitions* - Create, resize and delete LVM Volume Groups (VGs) - Create, resize, delete, format and mount LVM Logical Volumes (LVs) - Create, resize, delete, partition, format and mount Software RAID devices - Edit properties of the devices - UI can be modeled similar to the system-config-lvm tool The items marked with (*) in above list are urgently required for the Gluster feature, and will be developed first. Comments / inputs welcome.