[ovirt-users] Ovirt 4.2pre Moving disks when VM is running

[Arman Khalatyan]

Perfect!
Very detail explanation.
For the moment I will simply ignore the warning message.
a.


On Mon, Nov 27, 2017 at 9:42 AM, Shani Leviim <sleviim at redhat.com> wrote:
> Hi,
> When you'll press 'ok', a snapshot of that disk's image chain (its Base
> volume) is created in the source storage domain, and the entire image chain
> is replicated in the destination storage domain.
> It doesn't effect the original disk, and meanwhile, the VM keep "act
> normally":
>
> - If the VM's actions only deal with reading the disk, creating its snapshot
> should be a simpler task.
> - In case the VM writes data to the disk, a new snapshot volume which
> contains only the changes (for simplifying, you can think the way "git diff"
> works) is being created on both source and destination targets.
> While the base volume is being copied from the source target to the
> destination target, those snapshot volumes (for disk's changes) get
> synchronized.
>
> When the disk's images on both source and destination targets are identical,
> the VM points to the 'new' image and deletes the old pointer.
> I.e. the disk was successfully moved.
>
> In case of any failure during the migration, since targeted destination
> contains only a snapshot of the original disk's image, the original image
> isn't being effected,
> So there won't be a data lose and operation just fails.
> Also, busy network can affect the migration's duration.
>
> More data about the process are available here:
> https://www.ovirt.org/develop/release-management/features/storage/storagelivemigration/
>
> Regards,
> Shani Leviim
>
> On Sun, Nov 26, 2017 at 5:38 PM, Arman Khalatyan <arm2arm at gmail.com> wrote:
>>
>> hi Sahni,
>> thanks for the details.
>> Looks like the live storage migration might fail on the heavy loaded
>> virtual machines. I just tried to move from nfs to iscsi storage(most of the
>> cases they moved w/o error), the message on the move dialog warns us  "!
>> moving following disks when VM is running", if we press "ok ! do it" what
>> are the consequences? it is not explained in the docs.
>> thank you beforehand
>> Arman.
>>
>>
>> Am 26.11.2017 2:12 nachm. schrieb "Shani Leviim" <sleviim at redhat.com>:
>>
>> Hi Arman,
>> VM's migration and disks migration are two different things:
>>
>> - Live storage migration:
>> A VM's disk can be moved to another storage domain while the VM is
>> running, by copying the disk's structure the destination domain.
>> The hard part of live storage migration is moving the active layer volumes
>> from one domain to another, while the VM is writing to those volumes.
>> By using a replication operation, the data is written to both source and
>> destination volumes.
>> When both volumes contain the same data, the block job operation can be
>> aborted, pivoting to the new disk.
>>
>> You may find more detailed information here:
>> https://www.ovirt.org/develop/release-management/features/storage/live-storage-migration-between-mixed-domains/
>>
>> - Live migration:
>> Provides the ability to move a running virtual machine between physical
>> hosts with no interruption to service.
>> The virtual machine remains powered on and user applications continue to
>> run while the virtual machine is relocated to a new physical host.
>> A running virtual machine can be live migrated to any host within its
>> designated host cluster.
>> Live migration of virtual machines does not cause any service
>> interruption.
>>
>> You may find some more information here:
>> https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Virtualization/3.5/html/Administration_Guide/sect-Migrating_Virtual_Machines_Between_Hosts.html#What_is_live_migration
>>
>> Hope it helps!
>>
>> Regards,
>> Shani Leviim
>>
>> On Fri, Nov 24, 2017 at 11:54 AM, Arman Khalatyan <arm2arm at gmail.com>
>> wrote:
>>>
>>> hi,
>>> I have some test enviroment with ovirt
>>> "4.2.0-0.0.master.20171114071105.gitdfdc401.el7.centos"
>>> 2hosts+2NFS-domains
>>>
>>> During the multiple disk movement between the domains I am getting this
>>> warning:
>>> Moving disks while the VMs are running.(this is not so scary red as in
>>> 4.1.x :) )
>>>
>>> What kind of problems can happen during the movement?
>>>
>>> Thanks,
>>> Arman.
>>> _______________________________________________
>>> Users mailing list
>>> Users at ovirt.org
>>> http://lists.ovirt.org/mailman/listinfo/users
>>
>>
>>
>