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From Paul Angus <>
Subject RE: Slow snapshots with KVM
Date Wed, 30 Jan 2013 20:59:39 GMT
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.


Paul Angus
S: +44 20 3603 0540 | M: +447711418784

-----Original Message-----
From: Andrei Mikhailovsky []
Sent: 30 January 2013 17:25
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

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