On Dec 02 2012 Stefan Richter wrote: > On Nov 26 Martin K. Petersen wrote: > > >>>>> "Stefan" == Stefan Richter <stefanr@xxxxxxxxxxxxxxxxx> writes: > > Stefan> I did not try "sg_write_same" on any of the devices; but since > > Stefan> the two SPC-3 devices are correctly identified as "fully > > Stefan> provisioned", won't issue WRITE SAME to them either. > ^[the kernel] > > > > What if you have an SSD behind one of them? > > At the moment I only have a single old SSD available which does not > implement ATA TRIM as far as I recall. > > And the two mentioned OXUF936QSE based SPC-3 devices are four-bay SATA disk > enclosures whose firmwares only support various RAID modes and require at > least two bays to be populated. I.e. I can't test them with the SSD for > now. But I suspect that they don't implement thin provisioning anyway, > particularly translation of WRITE SAME with UNMAP to ATA TRIM. > > But now I found another SPC-3 compliant device in my stash; a dual SATA > bridge based on OXUF934DSB which supports JBOD with 1...2 disks > alternatively to striping/ spanning/ mirroring over 2 disks. I attached > the old SSD to it, and its thin_provisioning sysfs attribute was shown as > 0 as well. "sg_write_same -U ..." on this device in the 10 and 16 byte > variants ended with Illegal Request/ Invalid command operation code, but > otherwise without discernible malfunction. > > > Stefan> Hence let's remove the no_report_opcodes and no_write_same > > Stefan> blacklist flags so that these commands can be used on > > Stefan> respectively capable targets. > > > > I just erred on the side of caution. If you are happy without belt and > > suspenders that's perfectly ok with me :) > > Blacklisting at first was definitely the right approach. But now that I > looked at a variety of older and newer devices, I am confident that the > general Inquiry_Data.Version >= SPC-3 test keeps the wackier among the > SBP-2 devices safe enough. (I followed up with https://git.kernel.org/linus/b0ea5f19d3d8.) > Of course it remains to be seen what happens with ATA TRIM enabled SSDs > behind the newer SPC-3 compliant bridges, but at this time the risk with > those seems low. I now tested - ONNTO dataTale RSM4QO (OXUF936QSE) with two Samsung 840 Pro in RAID 0, - ONNTO dataTale RSM4QO (OXUF936QSE) with two Samsung 840 Pro in RAID 1, - IOI FWBU2-DSATA12 (OXUF934DSB) with one Samsung 840 Pro and kernel 3.9. $ grep . /sys/class/scsi_disk/42\:0\:0\:0/*prov* /sys/class/scsi_disk/42:0:0:0/provisioning_mode:full /sys/class/scsi_disk/42:0:0:0/thin_provisioning:0 # sg_opcodes /dev/sdg Ext Hard Disk Peripheral device type: disk Report supported operation codes: operation not supported # sg_write_same --10 --lba=1 /dev/sdg Write same(10) command not supported # sg_write_same --16 --lba=1 /dev/sdg Write same(16) command not supported # sg_write_same --32 --lba=1 /dev/sdg Write same: pass through os error: Invalid argument Write same(32) command failed I will send a patch which reverts the drivers/firewire/sbp2.c hunk of https://git.kernel.org/linus/54b2b50c20a6 "[SCSI] Disable WRITE SAME for RAID and virtual host adapter drivers". (As an aside, sbp2.c implements a transport, not a virtual host adapter.) -- Stefan Richter -=====-===-= ==-- -==== http://arcgraph.de/sr/ -- 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
