[sheepdog-users] Snashot and backup
namei.unix at gmail.com
Thu Dec 6 15:54:38 CET 2012
On 12/06/2012 10:01 PM, Valerio Pachera wrote:
> Hi all, may anybody write me same examples on how to backup a vdi disk?
> I've been looking for documentation but I didn't find anything.
what do you mean by 'backup a vdi'?
If you mean reading it from Sheepdog cluster and store it as a local
image, you can actually convert it by:
$ qemu-img sheepdog:image -O format(such as qcow2) backup_name
Then you can see a image named backup_name on your local disk. I assume
you meant this kind of 'backup'. Actually we have another 'collie vdi
backup' to backup only the differential data between snapshots. See more at
> To backup a vdi disk:
> 1) the guest that uses it has to be off
The guest has to be off to get a consistent 'backup', though you can
convert it on the fly. (I am not sure about this because I never try to
convert a image when it is running).
> 2) the guest may be running but it's better if it's off
> 3) it doesn't matter if it's running or not
> Backup can be don only from a snapshot?
> True or False
You can convert whatever images you see in the 'collie vdi list'
> Backup is never intend like a copy of a file that I can store elsewhere.
> I'm used to make copies of file (.qcow / .raw) or block devices (dd of
> a logival volume) to a nas.
> With sheepdog a copy is still inside the cluster, there's no way to
> 'export' a vdi disk to an external storage.
> Is that right?
Besides 'qemu-img convert', we can also use 'vdi
read/write/setattr/getattr' the sheepdog images.
You can even mount those images locally via sheepfs.
> I made a clone of a snapshot of the vdi named 'squeeze'.
> From vdi list I saw
> Name Id Size Used Shared Creation time VDI id Copies Tag
> c squeeze_clone 1 10 GB 152 MB 2.6 GB 2012-12-06 14:49 d8d65 2
> Later I 'c' has gone away.
> squeeze_clone 2 10 GB 0.0 MB 2.7 GB 2012-12-06 14:57 d8d66 2
> When is the 'c' going away?
What did you do between the time it went away? I can't reproduce the
problem. The 'c' indicator always hangs there on my box
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