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From Wido den Hollander <>
Subject Re: Your thoughts on using Primary Storage for keeping snapshots
Date Mon, 16 Feb 2015 15:04:07 GMT

On 16-02-15 15:38, Logan Barfield wrote:
> I like this idea a lot for Ceph RBD.  I do think there should still be
> support for copying snapshots to secondary storage as needed (for
> transfers between zones, etc.).  I really think that this could be
> part of a larger move to clarify the naming conventions used for disk
> operations.  Currently "Volume Snapshots" should probably really be
> called "Backups".  So having "snapshot" functionality, and a "convert
> snapshot to backup/template" would be a good move.

I fully agree that this would be a very great addition.

I won't be able to work on this any time soon though.


> Thank You,
> Logan Barfield
> Tranquil Hosting
> On Mon, Feb 16, 2015 at 9:16 AM, Andrija Panic <> wrote:
>> BIG +1
>> My team should submit some patch to ACS for better KVM snapshots, including
>> whole VM snapshot etc...but it's too early to give details...
>> best
>> On 16 February 2015 at 13:01, Andrei Mikhailovsky <> wrote:
>>> Hello guys,
>>> I was hoping to have some feedback from the community on the subject of
>>> having an ability to keep snapshots on the primary storage where it is
>>> supported by the storage backend.
>>> The idea behind this functionality is to improve how snapshots are
>>> currently handled on KVM hypervisors with Ceph primary storage. At the
>>> moment, the snapshots are taken on the primary storage and being copied to
>>> the secondary storage. This method is very slow and inefficient even on
>>> small infrastructure. Even on medium deployments using snapshots in KVM
>>> becomes nearly impossible. If you have tens or hundreds concurrent
>>> snapshots taking place you will have a bunch of timeouts and errors, your
>>> network becomes clogged, etc. In addition, using these snapshots for
>>> creating new volumes or reverting back vms also slow and inefficient. As
>>> above, when you have tens or hundreds concurrent operations it will not
>>> succeed and you will have a majority of tasks with errors or timeouts.
>>> At the moment, taking a single snapshot of relatively small volumes (200GB
>>> or 500GB for instance) takes tens if not hundreds of minutes. Taking a
>>> snapshot of the same volume on ceph primary storage takes a few seconds at
>>> most! Similarly, converting a snapshot to a volume takes tens if not
>>> hundreds of minutes when secondary storage is involved; compared with
>>> seconds if done directly on the primary storage.
>>> I suggest that the CloudStack should have the ability to keep volume
>>> snapshots on the primary storage where this is supported by the storage.
>>> Perhaps having a per primary storage setting that enables this
>>> functionality. This will be beneficial for Ceph primary storage on KVM
>>> hypervisors and perhaps on XenServer when Ceph will be supported in a near
>>> future.
>>> This will greatly speed up the process of using snapshots on KVM and users
>>> will actually start using snapshotting rather than giving up with
>>> frustration.
>>> I have opened the ticket CLOUDSTACK-8256, so please cast your vote if you
>>> are in agreement.
>>> Thanks for your input
>>> Andrei
>> --
>> Andrija Panić

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