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From Ahmad Emneina <>
Subject Re: Slow snapshots with KVM
Date Wed, 30 Jan 2013 21:14:49 GMT
KVM does a snapshot of the whole disk, as opposed to delta's like
xenserver. Which is why your kvm snapshots take ages to copy to secondary

On Wed, Jan 30, 2013 at 12:59 PM, Paul Angus <>wrote:

> Hi Andrei,
> CloudStack snapshots are currently best thought off as back-ups rather
> than snapshots.
> Although CloudStack leverages the hypervisor's native snapshot technology,
> it then copies/movies the hypervisor level snapshot to secondary storage.
>  CloudStack doesn't declare the snapshot task finished until the snapshot
> has finished copying to secondary storage which can take a long time
> especially if you've got 100GB+ images.
> Given that you can't simply 'roll-back' a VM to its snapshot state, as I
> say, it's best to think of them as backups rather than snapshots.
> Regards,
> Paul Angus
> S: +44 20 3603 0540 | M: +447711418784
> -----Original Message-----
> From: Andrei Mikhailovsky []
> Sent: 30 January 2013 17:25
> To:
> Subject: Slow snapshots with KVM
> Hello guys,
> I was wondering if there is a way to speed up the creation of snapshots in
> CS + KVM? It seems that every time the snapshot is created an entire vm
> disk image is copied over from primary to secondary storage which could
> take ages if your images are 100GB+. I remember that taking images in
> vmware / xenserver takes minutes if not seconds. Does the problem relate to
> KVM or is it a CloudStack design issue of separating primary and secondary
> storage?
> Many thanks
> Andrei
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