Re: [Qemu-devel] Crash: When Host HDD is full

["Daniel P. Berrange" <berrange@redhat.com>]

On Thu, Jul 12, 2007 at 07:12:58PM +0300, Avi Kivity wrote:
> Mike Swanson wrote:
> >On Wednesday 11 July 2007 08:19:48 Alexey Eremenko wrote:
> >  
> >>Problem 1:
> >>When Host HDD is full, all guests simply crash. Tried with dynamically
> >>growing .VMDK hard disk.
> >>
> >>It shouldn't happen. For example, both VirtualPC and VirtualBox pause
> >>all VMs, and gray their displays when something like that happens.
> >>    
> >
> >IMO, it's a non-issue; you probably shouldn't be letting your filesystems 
> >to become full in the first place, much less running VMs on it. 
> 
> Well, he shouldn't, but neither should qemu crash or corrupt data.

It should be propagating any IO errors in the host back up to the guest
OS as IDE errors. The guest OS will see these and (in the case of Linux)
take the filesystem offline. There should be no crash or data corruption.
While any outstanding writes will not have been flushed with any reasonable
filesystem it will recover upon reboot, either by fsck, or trivially 
recovering the journal & maintaining filesystem integrity.

Potentially ENOSPC could be handled as a special case by pausing the 
guest, but in general I/O errors can be propagated back to guest for
handling (even if the guest merely takes things ofline).

Dan.
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