[Engine-devel] [Engine-Devel] OvfDataUpdater

Liron Aravot laravot at redhat.com
Mon Nov 19 13:58:55 UTC 2012 


----- Original Message -----
> From: "Michael Kublin" <mkublin at redhat.com>
> To: "Liron Aravot" <laravot at redhat.com>
> Cc: engine-devel at ovirt.org
> Sent: Monday, November 19, 2012 3:44:41 PM
> Subject: Re: [Engine-devel] [Engine-Devel] OvfDataUpdater
> 
> 
> 
> ----- Original Message -----
> > From: "Liron Aravot" <laravot at redhat.com>
> > To: "Michael Kublin" <mkublin at redhat.com>
> > Cc: engine-devel at ovirt.org
> > Sent: Monday, November 19, 2012 3:34:11 PM
> > Subject: Re: [Engine-devel] [Engine-Devel] OvfDataUpdater
> > 
> > 
> > 
> > ----- Original Message -----
> > > From: "Michael Kublin" <mkublin at redhat.com>
> > > To: "Liron Aravot" <laravot at redhat.com>
> > > Cc: engine-devel at ovirt.org
> > > Sent: Monday, November 19, 2012 3:28:06 PM
> > > Subject: Re: [Engine-devel] [Engine-Devel] OvfDataUpdater
> > > 
> > > 
> > > 
> > > ----- Original Message -----
> > > > From: "Liron Aravot" <laravot at redhat.com>
> > > > To: "Michael Kublin" <mkublin at redhat.com>
> > > > Cc: engine-devel at ovirt.org
> > > > Sent: Monday, November 19, 2012 3:17:04 PM
> > > > Subject: Re: [Engine-devel] [Engine-Devel] OvfDataUpdater
> > > > 
> > > > 
> > > > 
> > > > ----- Original Message -----
> > > > > From: "Michael Kublin" <mkublin at redhat.com>
> > > > > To: "Liron Aravot" <laravot at redhat.com>
> > > > > Cc: engine-devel at ovirt.org
> > > > > Sent: Monday, November 19, 2012 3:03:23 PM
> > > > > Subject: Re: [Engine-devel] [Engine-Devel] OvfDataUpdater
> > > > > 
> > > > > 
> > > > > 
> > > > > ----- Original Message -----
> > > > > > From: "Liron Aravot" <laravot at redhat.com>
> > > > > > To: "Mike Kolesnik" <mkolesni at redhat.com>
> > > > > > Cc: engine-devel at ovirt.org, "Michael Kublin"
> > > > > > <mkublin at redhat.com>
> > > > > > Sent: Monday, November 19, 2012 2:52:56 PM
> > > > > > Subject: Re: [Engine-devel] [Engine-Devel] OvfDataUpdater
> > > > > > 
> > > > > > 
> > > > > > 
> > > > > > ----- Original Message -----
> > > > > > > From: "Mike Kolesnik" <mkolesni at redhat.com>
> > > > > > > To: "Liron Aravot" <laravot at redhat.com>
> > > > > > > Cc: engine-devel at ovirt.org, "Michael Kublin"
> > > > > > > <mkublin at redhat.com>
> > > > > > > Sent: Monday, November 19, 2012 2:44:56 PM
> > > > > > > Subject: Re: [Engine-devel] [Engine-Devel] OvfDataUpdater
> > > > > > > 
> > > > > > > > 
> > > > > > > > 
> > > > > > > > ----- Original Message -----
> > > > > > > > > From: "Liron Aravot" <laravot at redhat.com>
> > > > > > > > > To: engine-devel at ovirt.org
> > > > > > > > > Sent: Monday, November 19, 2012 2:03:57 PM
> > > > > > > > > Subject: [Engine-devel] [Engine-Devel] OvfDataUpdater
> > > > > > > > > 
> > > > > > > > > starting a new discussion thread.
> > > > > > > > > 
> > > > > > > > > ----- Original Message -----
> > > > > > > > > > From: "Mike Kolesnik" <mkolesni at redhat.com>
> > > > > > > > > > To: "Liron Aravot" <laravot at redhat.com>
> > > > > > > > > > Sent: Monday, November 19, 2012 12:42:10 PM
> > > > > > > > > > Subject: Re: [Engine-devel]  OvfAutoUpdater
> > > > > > > > > > 
> > > > > > > > > > I think 'version' is a more standard term for the
> > > > > > > > > > column
> > > > > > > > > > names.
> > > > > > > > > > 
> > > > > > > > > > Also in:  4. If succesfull - for each vm update the
> > > > > > > > > > ovf_generation
> > > > > > > > > > to
> > > > > > > > > > equal the db_generation.
> > > > > > > > > > I think you mean that the update should be to the
> > > > > > > > > > entity
> > > > > > > > > > version
> > > > > > > > > > you
> > > > > > > > > > initially selected.
> > > > > > > > > > 
> > > > > > > > 1. I think should be version = version +1;
> > > > > > the version will be the db_generation that was loaded when
> > > > > > we
> > > > > > loaded
> > > > > > the vm/template.
> > > > > > for example - if the vm/template was updated twice between
> > > > > > OvfUpdater
> > > > > > runs, we will need to increment twice - so incrementing by
> > > > > > one
> > > > > > will
> > > > > > cause another unneeded ovf update for that vm.
> > > > > I am talking about ovfVersion or how you called it.
> > > > me too,
> > > > if we update the vm three times between OvfAutoUpdater runs ,
> > > > we
> > > > will
> > > > have the following values in the loaded vm for example:
> > > > db_generation 8
> > > > ovf_generation 5
> > > > 
> > > > when we perform the ovf update , ovf_generation should be set
> > > > to
> > > > 8
> > > > and not to 6, as version '8' is the version that we wrote the
> > > > ovf
> > > > metadata of.
> > > These should be written in wiki, with remarks that values which
> > > were
> > > retrieved
> > > from DB together.
> > > > > > > > 2. Now the quartz is automatic process, updateVmInSpm
> > > > > > > > it
> > > > > > > > is
> > > > > > > > spm
> > > > > > > > operation -it means it can trigger a reconstruct
> > > > > > > > and spm election.
> > > > > > 2. updateVmInSpm command would be changed so it won't
> > > > > > trigger
> > > > > > failover, will add that to the wiki.
> > > > > > > > 3. How your solution is handling a case of
> > > > > > > > hotPlug/hotUnplug/remove/add of vm disks. vm_static is
> > > > > > > > not
> > > > > > > > usually
> > > > > > > > updated.
> > > > > > Whenever will be a command that locks a vm/template, you
> > > > > > will
> > > > > > have
> > > > > > an
> > > > > > option during the unlock to specify if the version need to
> > > > > > be
> > > > > > incremented, you'll be able to increment it also yourself.
> > > > > > The HotUnPlug command does lock the vm and during
> > > > > > endSuccesfully
> > > > > > attempt to update the vm in spm, so it will increment the
> > > > > > db_version/generation instead.
> > > > > > > 
> > > > > addDisk, removeDisk, hotPlug/unPlug not locking a vm.
> > > > > Also, as far as I know LockVm/UnLockVm it is operation on
> > > > > vm_dynamic
> > > > > and not
> > > > > vm_static.
> > > > 
> > > > hotplug acquires memory lock on the vm and has no async tasks
> > > > if
> > > > I
> > > > recall correctly.
> > > Yes, correct and what? These what I said, vm_static is not
> > > updated.
> > you will just call the dao method for incrementing the
> > db_generation,
> > you don't have to perform vm_static update.
> > > > adddisk acquires shared lock on the vm which is problematic
> > > > with
> > > > today flow as well - as you have a race during updateVmInSpm,
> > > > it
> > > > should be fixed regardless of the OvfAutoUpdater.
> > > It is not answer on my question. How ovf will be updated? How you
> > > understand
> > > that ovf of vm should be updated?
> > 
> > the ovf will be updated when you increment the db_generation value
> > instead of calling updateVmInSpm().
> > you will be able to do that from the dao directly when you want, or
> > when you unlock a vm/template.
> > when you will update the db_generation, the vm/template would be
> > picked up by OvfUpdater as it's db_generation is different than its
> > ovf_generation.
> 1. Update of ovfs is not related to locks and it should not be, I
> don't understand why
> you link them.
> 2. Races - your automatic process and couple of add disk commands.
> You will miss update
> of ovf.
> 3. Also when you will add increase of generation it is not clear from
> your design

1+2 The OvfAutoUpdater is not related and doesn't acquire any locks.

as of today, if you call updateVmInSpm without performing the operations with lock on the vm you'll have a race - for example, in addDisk (shared calls, two updateVmInSpm might be executed in the same time and you can't know with with ovf you'll end).

therefore, when updating the ovf_generation you should have a lock somewhere otherwise you might miss updates because of races.
if today updatevminspm is called without locks and have races, it needs to be fixed unrelated to it.

3. you will increase the generation whenever you made updateVmInSpm.
> > > > > 
> > > > > > > Also consider snapshots & vNICs which affect the VM
> > > > > > > state.
> > > > > > Whatever affect the vm state and triggers updateVmInSpm
> > > > > > today
> > > > > > will
> > > > > > continue to, it can be added to flows which don't do that
> > > > > > today.
> > > > > > > 
> > > > > > > > 4. Reconstruct/Recovery - updateVmInSpm should be
> > > > > > > > called
> > > > > > > > on
> > > > > > > > all
> > > > > > > > vms,
> > > > > > > > no matter if they were updated.
> > > > > > 
> > > > > > Ofcourse, it's being taken care of.
> > > > > How?
> > > > we don't have ovf's of the vms when we reconstruct as we don't
> > > > have
> > > > master domain - so we should set the ovf_generation of the vms
> > > > to
> > > > be
> > > > 0 - which will cause ovfautoupdater to copy the vm metadata.
> > > I did not understand that statement and how it is related.
> > OvfAutoUpdater will get those vms for update as db_generation is
> > different than ovf_generation.
> > > > a performance improvement may be introduced later on in case of
> > > > wrong
> > > > master version, but that's not related to the ovfautoupdater.
> > > I don't understand connection to performance.
> > > Now you are replacing a calls to VmCommand.updateVmInSpm() one of
> > > them it
> > > is at reconstruct flow, and you should handle it also and add it
> > > to
> > > wiki.
> > answered below, OvfAutoUpdater will get those vms for update as
> At reconstruct all vms are updated. So it is not related to
> generation.
> How you handle these case?

when doing reconstruct, the ovf_generation of all vms is set to 0 as we don't have them on the master domain.
ovfupdater will get this vms for update as ovf_generation < db_generation, will copy the vm ovf and set db_genertion to ovf_generation.

> > db_generation is different than ovf_generation.
> > > > > > > > 
> > > > > > > > > > Regards,
> > > > > > > > > > Mike
> > > > > > > > > > 
> > > > > > > > > > ----- Original Message -----
> > > > > > > > > > > http://wiki.ovirt.org/wiki/Feature/OvfAutoUpdater
> > > > > > > > > > > 
> > > > > > > > > > > Hi all, i'll be glad if you could review the wiki
> > > > > > > > > > > page
> > > > > > > > > > > of
> > > > > > > > > > > OvfAutoUpdater, if you have any suggestions or
> > > > > > > > > > > ideas
> > > > > > > > > > > please
> > > > > > > > > > > let
> > > > > > > > > > > me
> > > > > > > > > > > know.
> > > > > > > > > > > 
> > > > > > > > > > > http://wiki.ovirt.org/wiki/Feature/OvfAutoUpdater
> > > > > > > > > > > 
> > > > > > > > > > > short preview from the wiki:
> > > > > > > > > > > vm/template configurations (including disks info)
> > > > > > > > > > > are
> > > > > > > > > > > stored
> > > > > > > > > > > on
> > > > > > > > > > > the
> > > > > > > > > > > master storage domain for backup purposes,
> > > > > > > > > > > import/export
> > > > > > > > > > > and
> > > > > > > > > > > also
> > > > > > > > > > > to
> > > > > > > > > > > provide the abillity to run VMs without having a
> > > > > > > > > > > running
> > > > > > > > > > > engine/db.
> > > > > > > > > > > Currently ovf update is done synchronously when
> > > > > > > > > > > performing
> > > > > > > > > > > various
> > > > > > > > > > > operations on vms/templates - update, save,
> > > > > > > > > > > adding/removing
> > > > > > > > > > > a
> > > > > > > > > > > disk,
> > > > > > > > > > > etc. What's more, currently updating the ovf
> > > > > > > > > > > (updateVM
> > > > > > > > > > > vdsm
> > > > > > > > > > > call)
> > > > > > > > > > > is
> > > > > > > > > > > usually done within a transcation.
> > > > > > > > > > > 
> > > > > > > > > > > The idea behined OvfAutoUpdater is to perform
> > > > > > > > > > > batch
> > > > > > > > > > > ovf
> > > > > > > > > > > update
> > > > > > > > > > > operations that aggregate all outstanding updates
> > > > > > > > > > > per
> > > > > > > > > > > data
> > > > > > > > > > > center.
> > > > > > > > > > > These updates will be done in specifed time
> > > > > > > > > > > intervals
> > > > > > > > > > > which
> > > > > > > > > > > will
> > > > > > > > > > > reduce XML-RPC calls and will enable the removal
> > > > > > > > > > > of
> > > > > > > > > > > this
> > > > > > > > > > > syncronous
> > > > > > > > > > > vdsm call from all over the code.
> > > > > > > > > > > 
> > > > > > > > > > > Thanks,
> > > > > > > > > > > Liron Aravot.
> > > > > > > > > > > _______________________________________________
> > > > > > > > > > > Engine-devel mailing list
> > > > > > > > > > > Engine-devel at ovirt.org
> > > > > > > > > > > http://lists.ovirt.org/mailman/listinfo/engine-devel
> > > > > > > > > > > 
> > > > > > > > > > 
> > > > > > > > > _______________________________________________
> > > > > > > > > Engine-devel mailing list
> > > > > > > > > Engine-devel at ovirt.org
> > > > > > > > > http://lists.ovirt.org/mailman/listinfo/engine-devel
> > > > > > > > > 
> > > > > > > > _______________________________________________
> > > > > > > > Engine-devel mailing list
> > > > > > > > Engine-devel at ovirt.org
> > > > > > > > http://lists.ovirt.org/mailman/listinfo/engine-devel
> > > > > > > > 
> > > > > > > 
> > > > > > 
> > > > > 
> > > > 
> > > 
> > 
>

More information about the Engine-devel mailing list