[pve-devel] some news for snapshots

Alexandre DERUMIER aderumier at odiso.com
Mon Aug 27 18:17:57 CEST 2012


>>I mean I see the problem with backup, but external hnapshot has much more problems, 
>>because you need to do a merge after the backup? 

Yes,we need to merge if we want to delete the snapshot after the backup.
and now, this is from parent to children.


> By making the snapshot-file argument of the monitor and QMP command 
> optional, that could be used as a request to make the snapshot internally 
> instead of to an external file.

so this is using the blockdev-snapshot-sync without file argument to do snapshot internal, in the current qcow2.
I talk with qemu mailing, this is not planned for now.

>> However, without live block migration of an 
> internal snapshot, there is no way to make a backup of an internal snapshot 
> while still leaving the VM running, so this feature is not planned at the 
> present. For now, the snapshot-file argument is required, and only external 
> snapshots are implemented. 

Yes, indeed with external snapshot, we can backup the parent file.
This is good for backup only I think.

Internal snapshot should be the way to handle snapshot/rollback.
(do a snapshot before doing a critical update by exemple, and rollback in something goes wrong without need to merge)


sheepdog,rbd,nexenta can do the both.
(you can do a fast snapshot/rollback, or export an image at snapversion  to do backup)





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

De: "Dietmar Maurer" <dietmar at proxmox.com> 
À: "Alexandre DERUMIER" <aderumier at odiso.com> 
Cc: pve-devel at pve.proxmox.com 
Envoyé: Lundi 27 Août 2012 17:51:52 
Objet: RE: [pve-devel] some news for snapshots 

> Just found the following comment: 
> http://wiki.qemu.org/Features/Snapshots 
> 
> -------------- 
> internal snapshots 
> 
> By making the snapshot-file argument of the monitor and QMP command 
> optional, that could be used as a request to make the snapshot internally 
> instead of to an external file. However, without live block migration of an 
> internal snapshot, there is no way to make a backup of an internal snapshot 
> while still leaving the VM running, so this feature is not planned at the 
> present. For now, the snapshot-file argument is required, and only external 
> snapshots are implemented. 
> --------------- 
> 
> Do you fully understand that? 

I mean I see the problem with backup, but external hnapshot has much more problems, 
because you need to do a merge after the backup? 



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