[pve-devel] consistent backups / snapshots

[Alexandre DERUMIER]

Am 22.11.2012 14:41, schrieb Alexandre DERUMIER: 
> I see 2 ways : 
> 
> - snapshot with vmstate. (so pending write in memory are saved). 

>>Does this work with rbd snap? 

Yes. (Dietmar has implemented it with creating a rbd volume to store the vmstate).
Just try with the proxmox gui ;)


> - implement qemu guest agent qmp protocol ,and send fs-freeze qmp command to freeze the filesystem, before doing the snapshot. 
> (I have seny some prelimary patches some months ago, need to be polish) 

>>Patches? this sounds experimental - patches for guest kernel? For qemu? 

patches for pve-qemu-server ;)

http://wiki.qemu.org/Features/QAPI/GuestAgent

- First, you need to install qemu-ga deamon in your guest.
- then pass 
-chardev qga_proxy,id=qga0 \
 -device virtio-serial \
 -device virtserialport,chardev=qga0,name=org.qemu.guest_agent.0
 -qmp tcp:localhost:4444,server

to kvm command line.

and then implemented the qemu-ga protocol.
(It's like qmp, but with some minor changes in protocol (check the wiki)



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

De: "Stefan Priebe - Profihost AG" <s.priebe at profihost.ag> 
À: "Alexandre DERUMIER" <aderumier at odiso.com> 
Cc: pve-devel at pve.proxmox.com 
Envoyé: Jeudi 22 Novembre 2012 14:50:16 
Objet: Re: [pve-devel] consistent backups / snapshots 

Am 22.11.2012 14:41, schrieb Alexandre DERUMIER: 
> I see 2 ways : 
> 
> - snapshot with vmstate. (so pending write in memory are saved). 

Does this work with rbd snap? 

> - implement qemu guest agent qmp protocol ,and send fs-freeze qmp command to freeze the filesystem, before doing the snapshot. 
> (I have seny some prelimary patches some months ago, need to be polish) 

Patches? this sounds experimental - patches for guest kernel? For qemu? 

Greets, 
Stefan 

> ----- Mail original ----- 
> 
> De: "Stefan Priebe - Profihost AG" <s.priebe at profihost.ag> 
> À: pve-devel at pve.proxmox.com 
> Envoyé: Jeudi 22 Novembre 2012 11:35:05 
> Objet: [pve-devel] consistent backups / snapshots 
> 
> Hello list, 
> 
> i was trying to make consistent rbd snapshots. What is the recommanded 
> method in PVE / qemu to flush all buffers / be able to make a consistent 
> backup? 
>