[pve-devel] create snapshots

Alexandre DERUMIER aderumier at odiso.com
Fri Aug 31 13:21:39 CEST 2012


>>But I am quite unsure with nexenta - how can we make sure that the nexenta server 
>>received all data before we do a snapshot? 
I think it the same than other, if vm_stop is call, bdrv_drain_all,bdrv_flush_all will use libiscsi.

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.



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

De: "Dietmar Maurer" <dietmar at proxmox.com> 
À: "Alexandre DERUMIER (aderumier at odiso.com)" <aderumier at odiso.com>, pve-devel at pve.proxmox.com 
Envoyé: Vendredi 31 Août 2012 12:56:25 
Objet: RE: create snapshots 

> I wonder it is would be safe to call an external script to create the snapshot 
> there? 
> Or is there still some data in the qemu block driver cache, or the host cache? 

vm_stop calls: 

bdrv_drain_all(); 
bdrv_flush_all(); 

so that will at least try to flush data. 

But I am quite unsure with nexenta - how can we make sure that the nexenta server 
received all data before we do a snapshot? 




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Alexandre D e rumier 

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