On 02/03/2017 03:45 PM, Martin K. Petersen wrote: >>>>>> "Jens" == Jens Axboe <axboe@xxxxxxxxx> writes: > >>> I think we should fix sd.c to only send WRITE SAME if either of the >>> variants are explicitly listed as supported through REPORT SUPPORTED >>> OPERATION CODES, or maybe through a whitelist if there are important >>> enough devices. > > Jens> Yep > > I hate it too. But the reason it's assumed on is that there is > essentially no heuristic that works. Just like we assume that READ > always works. > > Out of the ~200 devices I have access to in the lab: > > - 100% of the SAS/FC disk drives and SSDs support WRITE SAME > - Only 2 out of about 50 different drive models support RSOC > - About half of the arrays support WRITE SAME(10/16) > - None of the arrays I have support RSOC > > So even if we were to entertain using RSOC for "enterprise" transport > classes (which I concur would be nice for other reasons), it wouldn't > solve the WRITE SAME problem... We're at (almost) -rc7 time, we have to do more than hand wave about this. What's the plan for 4.10 final? -- Jens Axboe
