On Gwe, 2006-03-24 at 07:38 -0500, Jeff Garzik wrote: > > A pure SCSI abstraction doesn't allow for shared head scheduling which > > you will need to scale Xen sanely on typical PC boxes. > > Not true at all. If you can do it with a block device, you can do it > with a SCSI block device. I don't believe this is true. The complexity of expressing sequences of command ordering between virtual machines acting in a co-operative but secure manner isn't as far as I can see expressable sanely in SCSI TCQ > > In fact, SCSI should make a few things easier, because the notion of > host+bus topology is already present, and notion of messaging is already > present, so you don't have to recreate that in a Xen block device > infrastructure. Those are the easy bits. > > are also always full of bits people got wrong, often critical bits like > > tagged queues and error sequences - things that break your journalled > > file system. > > This I'll grant you. And every one you get wrong is a corruptor.... Alan
