On Wed, Jul 18, 2012 at 11:53:38AM -0400, Christoph Hellwig wrote: > On Wed, Jul 18, 2012 at 08:42:21AM -0500, Anthony Liguori wrote: > > > > If you add support for a new command, you need to provide userspace > > a way to disable this command. If you change what gets reported for > > VPD, you need to provide userspace a way to make VPD look like what > > it did in a previous version. > > > > Basically, you need to be able to make a TCM device behave 100% the > > same as it did in an older version of the kernel. > > > > This is unique to virtualization due to live migration. If you > > migrate from a 3.6 kernel to a 3.8 kernel, you need to make sure > > that the 3.8 kernel's TCM device behaves exactly like the 3.6 kernel > > because the guest that is interacting with it does not realize that > > live migration happened. > > I don't think these strict live migration rules apply to SCSI targets. > > Real life storage systems get new features and different behaviour with > firmware upgrades all the time, and SCSI initiators deal with that just > fine. > I don't see any reason to be more picky just because we're > virtualized. Presumably initiators are shut down for target firmware upgrades? With virtualization your host can change without guest shutdown. You can also *lose* commands when migrating to an older host. -- MST -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
