On Wed, 01 Jun 2011 16:35:03 -0500
Anthony Liguori <anth...@codemonkey.ws> wrote:
> On 06/01/2011 04:12 PM, Luiz Capitulino wrote:
> > Hi there,
> >
> > There are people who want to use QMP for thin provisioning. That's, the VM
> > is
> > started with a small storage and when a no space error is triggered, more
> > space
> > is allocated and the VM is put to run again.
> >
> > QMP has two limitations that prevent people from doing this today:
> >
> > 1. The BLOCK_IO_ERROR doesn't contain error information
> >
> > 2. Considering we solve item 1, we still have to provide a way for clients
> > to query why a VM stopped. This is needed because clients may miss the
> > BLOCK_IO_ERROR event or may connect to the VM while it's already stopped
> >
> > A proposal to solve both problems follow.
> >
> > A. BLOCK_IO_ERROR information
> > -----------------------------
> >
> > We already have discussed this a lot, but didn't reach a consensus. My
> > solution
> > is quite simple: to add a stringfied errno name to the BLOCK_IO_ERROR event,
> > for example (see the "reason" key):
> >
> > { "event": "BLOCK_IO_ERROR",
> > "data": { "device": "ide0-hd1",
> > "operation": "write",
> > "action": "stop",
> > "reason": "enospc", }
>
> you can call the reason whatever you want, but don't call it stringfied
> errno name :-)
>
> In fact, just make reason "no space".
You mean, we should do:
"reason": "no space"
Or that we should make it a boolean, like:
"no space": true
I'm ok with either way. But in case you meant the second one, I guess
we should make "reason" a dictionary so that we can group related
information when we extend the field, for example:
"reason": { "no space": false, "no permission": true }
