Re: [Qemu-devel] [PATCH v2 0/5]: QMP: Proper thin provisioning support

[Luiz Capitulino]

On Wed, 3 Aug 2011 18:31:31 +0200
Christoph Hellwig <address@hidden> wrote:

> > It's already possible for QMP clients to implement this feature by using
> > the BLOCK_IO_ERROR event. However, the event can be missed. When this
> > happens QMP clients need a way to query if any block device has hit a
> > no space condition.
> 
> We have a mode where we stop the VM when it hits ENOSPC, and that is
> the only reliably way to handle it. 

This series just complements that mode by allowing a mngt application
to query which device triggered the ENOSPC. Well, that's my intention :)

> One that ENOSPC gets returned
> to the guest we don't know that it was an ENOSPC, and the guest will
> usually simply shut the filesystem down.  This could be worked around
> by implementing full T10 logical provisioning support, but very few
> guests actually support it properly.  And it won't work with ide disks
> at all, and for virtio we'd have to implement it first.

Seems interesting, but the current solution is guest independent.