[pve-devel] VM snapshot problem

Alexandre DERUMIER aderumier at odiso.com
Fri Aug 24 13:09:41 CEST 2012


>>What exactly is the interesting part? 
Nothing particular, but seeing how other solution implement snasphot is always good ;)


>>Why not? I thought one can specify that with the qmp command? 

oh maybe for qcow2 can we use the original file as target ?

-> { "execute": "blockdev-snapshot-sync", "arguments": { "device": "ide-hd0",
                                                         "snapshot-file":
                                                        "/some/place/my-image",
                                                        "format": "qcow2" } }



>>I still think we should use internal snapshots. That live merge/commit 
>>proposal sound like a bad idea to me. 
Yes, seem difficult to maintain.
Also for rollback, we need use on the snapshot file in the qemu command line file=...

>>I just though we can use external snapshots when there is no other 
>>way to do it. 
>>We can even disable 'remove snapshot' support for that case (simply do not allow 
>>to remove intermediate snapshots)? 
I don't know. When you do a snapshot, the new datas are written in the snapshot file.
So,I think we need to merge it if we remove the snapshot. (removing the snapshot is merging it)

Internal snapshot is more easy, as datas are in the file, we only need to "qemu-img snasphot -d" to remove the snapshot.
But it is possible online with qmp?

----- Mail original ----- 

De: "Dietmar Maurer" <dietmar at proxmox.com> 
À: "Alexandre DERUMIER" <aderumier at odiso.com> 
Cc: pve-devel at pve.proxmox.com 
Envoyé: Vendredi 24 Août 2012 12:46:26 
Objet: RE: VM snapshot problem 

> I found some interesting info on ovirt 
> 
> http://wiki.ovirt.org/wiki/Live_Snapshots 

What exactly is the interesting part? 

> Also, with live qemu snapshot, we can't do internal snapshots for qcow2 as 
> base image ? 

Why not? I thought one can specify that with the qmp command? 

> How does rollback work ? 
> Do we need to merge when we remove a snapshot ? 

I still think we should use internal snapshots. That live merge/commit 
proposal sound like a bad idea to me. 

I just though we can use external snapshots when there is no other 
way to do it. 

We can even disable 'remove snapshot' support for that case (simply do not allow 
to remove intermediate snapshots)? 




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Alexandre D e rumier 

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