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 |