On Tue, Sep 24 2013 at 9:49am -0400, Martin K. Petersen <martin.petersen@xxxxxxxxxx> wrote: > >>>>> "Mike" == Mike Snitzer <snitzer@xxxxxxxxxx> writes: > > Mike> So are there drives like this?: > Mike> 1) don't support RSOC > Mike> 2) do support WRITE SAME > Mike> 3) do populate VPD page with either WRITE SAME w/ discard bit set > Mike> or UNMAP? > > Yes. > > But again, the fundamental issue here is not the drives. It's the > controller firmware. I am not aware of a single SPI/SAS/FC drive that > does not support at least WRITE SAME(10). > > For DIX and T10 PI I have a capabilities mask that each HBA driver fills > out that tells the sd driver what the controller can do. And this is > combined with whatever the drive reports to figure out whether integrity > protection can be enabled. > > I have been contemplating doing something similar for "fancy" SCSI > commands. We could have a flag in the scsi host template that controls > whether the device supports WRITE SAME, EXTENDED COPY, etc. The > advantage being that we do the matching at discovery time instead of > once a WRITE SAME is issued. > > This would also permit HBA drivers to toggle the feature on a per > instance basis. I.e. if "RAID controller firmware rev is lower than XYZ, > do not support WRITE SAME". > > I'll do a PoC later today... Sounds promising, thanks! -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
