[pve-devel] create snapshots

Alexandre DERUMIER aderumier at odiso.com
Fri Aug 31 13:58:52 CEST 2012

>>What do you think? 
Yes, I think it's a really good idea !

----- 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 31 Août 2012 13:33:33 
Objet: RE: create snapshots 

> if we don't save vm_state, we need to freeze the filesystem. (qemu-ga call 
> xfs_freeze, which works for ext3, ext4, GFS2, XFS, and BTRFS) 
> Currently, I'm using directsync or writethrough cache mode to be sure that 
> the datas are always on disk. 
> (I have a fast nvram journal in my nexenta box). 
> I never add problem taking live disk snapshots and rollback them. 

Ok, so far so good ;-) 

Would it help if we split the "savevm" monitor command into 
several smaller command, which we can call individually: 

1.) snapshot_start 

* this is the first part of do_savevm() till vm_stop 

2.) dump_vm_state (or maybe we do this is step 1) 

* write state to some fd 

3.) snapshot_drive 

* simply call bdrv_snapshot_create(bs1, sn) for a single drive 

4.) snapshot_end 

* resume the VM (maybe this is a normal resume, so we can use the existing 'cont' 

What do you think? 




Alexandre D e rumier 

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