Re: [Qemu-block] [Qemu-devel] backup notifier fail policy

[Kevin Wolf]

Am 04.10.2016 um 18:02 hat Stefan Hajnoczi geschrieben:
> On Tue, Oct 04, 2016 at 01:55:30PM +0200, Kevin Wolf wrote:
> > Am 04.10.2016 um 12:41 hat Denis V. Lunev geschrieben:
> > > On 10/04/2016 12:34 PM, Kevin Wolf wrote:
> > > > Am 04.10.2016 um 11:23 hat Stefan Hajnoczi geschrieben:
> > > >> On Mon, Oct 03, 2016 at 02:07:34PM -0400, John Snow wrote:
> > > >>> Eh, regardless: If we're not using a STOP policy, it seems like the 
> > > >>> right
> > > >>> thing to do is definitely to just fail the backup instead of failing 
> > > >>> the
> > > >>> write.
> > > >> Even with a -drive werror=stop policy the user probably doesn't want
> > > >> guest downtime if writing to the backup target fails.
> > > > That's a policy decision that ultimately only the user can make. For one
> > > > user, it might be preferable to cancel the backup and keep the VM
> > > > running, but for another user it may be more important to keep a
> > > > consistent snapshot of the point in time when the backup job was started
> > > > than keeping the VM running.
> > > >
> > > > Kevin
> > > In this case policy for guest error and policy for backup
> > > error should be different policies or I have missed something.
> > 
> > I guess so.
> 
> There are separate error policies for -device and the blockjob.  Perhaps
> the blockjob error policy can be used in the write notifier code path if
> the failure occurs while writing to the backup target.

Isn't the block job policy used for the background copy? Or do you think
it's okay to use the same for both cases? That would mean that we stop
the VM even if it's just a background copy that fails.

Kevin

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