[pve-devel] snapshot improvements

Alexandre DERUMIER aderumier at odiso.com
Mon Sep 24 12:43:53 CEST 2012


>>We still stop the VM for a short period, and I think vm_stop() flush all driver cache. 
ok. savevm state live -> pausevm ->disk snapshots-> unpausevm 
seem good :)


I'll do tests this afternoon, I'll keep you in touch.


----- 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 24 Septembre 2012 12:35:35 
Objet: RE: [pve-devel] snapshot improvements 

> do you think image = size of memory if enough ? (if we have some bytes 
> more with incremental ?) 

PVE/QemuServer.pm: 

my $driver_state_size = 32; # assume 32MB is enough to safe all driver state; 
my $size = $conf->{memory} + $driver_state_size; 

> Also, any problem if some datas in vmstate need to be flushed to disk ? 

We still stop the VM for a short period, and I think vm_stop() flush all driver cache. 

> I see that you have add a "use writeback cache" patch, maybe it's for that 
> case ? 

no, this is just for the state file itself. 

> If yes, does it works with all devices (ide/scsi/virtio) ? (with any guest driver 
> version) 

why not? It is basically the same code as used for live migration. 

But yes, we need to carefully test it ;-) 


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