Re: [Xen-API] Storage XenMotion - Just sync

[Alexandre Kouznetsov <alk@xxxxxxxxxx>]

Hello.

El 09/01/13 16:27, Chris Dutton escribió:
> Hello,
>
> What I am trying to accomplish is keep a vm on one host (a) in sync with
> another vm on host (b). They are both using local storage for the SR,
> which led me to investigate SXM. But it looks like it does just a little
> more then I want.
>
>  From the Storage XenMotion wiki page:
>
> Each of a VM’s disks are snapshotted, and from the point of the snapshot
> onwards, all of the disk’s writes are synchronously mirrored to the
> destination storage repository. In the background, the snapshotted disk
> is copied to the destination location. Once a snapshot has finished
> copying, the next disk to be migrated is snapshot/mirrored.
>
> What I am hoping to do is everything except the last step (the actual
> migration).
Since you are not actually migrating the VM, maybe the sync is 
unnecessary (it might became obsolete in matter of seconds), but a copy 
of a snapshot.
Maybe this reference would help:
http://lists.xen.org/archives/html/xen-api/2013-01/msg00038.html
(and the rest of the thread, about vm-migrate behavior)

Note that the reference is about offline migration, but the mechanics is 
similar. In your case, you would probably want to do a snapshot of the 
VDI being used, and copy that snapshot to the other host, then attach it 
to the target VM.

> The sync does not necessarily have to be synchronous for my situation,
> so maybe run a sync as a cron job but when a sync happens I only want
> the deltas copied (not a full snapshot).
As I understand it, yhe method I suggested will not allow you to update 
the copy of the snapshot. Only create a new copy.

--
Alexandre Kouznetsov


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