[Sheepdog] Some setattr/getattr strangeness

[MORITA Kazutaka]

At Thu, 13 Oct 2011 13:35:06 +0100,
Chris Webb wrote:
> 
> MORITA Kazutaka <morita.kazutaka at lab.ntt.co.jp> writes:
> 
> > Sheepdog uses a corosync multicast for all global atomic operations,
> > so I think the correct way is to implement a SD_OP_ATOMIC_WRITE_OBJ
> > operation with the multicast.
> >
> > But this limits the size of a vdi attribute to the maximum multicast
> > size (a few hundreds KB?).  Is it okay for you?
> 
> Hi. That definitely wouldn't cause me any problems, as I'm only using them
> for locks (twenty bytes identifying uniquely what has claimed the vdi) and
> very simple textual properties (like a drive name). To be honest, I had
> assumed that they were intended for very small amounts of metadata like this
> rather than for bulk data storage, for which we have vdis themselves, and
> didn't realise they'd hold such large chunks of data successfully.

Okay, I'll create a patch to support atomic I/Os.

Thanks,

Kazutaka