Exactly. Joe Lawrence <joe.lawrence@xxxxxxxxxxx> wrote: >I'll away from the office the rest of the week for the Red Hat Summit, >but a few things tested today: > >*** Test 1 (repeated for both RAID1 and RAID10) > >Setup: RAID1/10, a single disk fails WRITE SAME with > [sense_key,asc,ascq]: [0x05,0x20,0x00] > >Result: the RAID md_personality error_handler was invoked for the disk > that kicked back Illegal Request. That disk was marked > faulty and write intent bitmaps started tracking chunks. WRITE > SAME to the other disks succeeded so MD didn't fail the parent > bio and therefore blkdev_issue_write_same was considered > successful. > > When the failed component disk is re-added to the RAID, the > write_same_max_bytes are recalculated and set to 0. Resync with > write intent bitmap properly mirrored the disk. > >This behavior seems reasonable, though one could argue that >write_same_max_bytes should be set to 0 for the MD device once any >WRITE >SAME fails. Better yet, the block layer could fall back to plain >WRITEs >without dropping the disk. > > >*** Test 2 > >Setup: RAID1, all member disks fail WRITE SAME with > [sense_key,asc,ascq]: [0x05,0x20,0x00]. > >Result: the first disk is kicked out of the RAID, but the second >remains > active. The block layer detected an error from > blkdev_issue_write_same, emits "mdXXX: WRITE SAME failed. > Manually zeroing" messages, but never prevents future WRITE > SAMEs from hitting this MD device. > > >*** Test 3 > >Setup: RAID10, all member disks fail WRITE SAME with > [sense_key,asc,ascq]: [0x05,0x20,0x00]. > >Result: all component disks are marked as faulty and lost page writes > occur on MD device! blkdev_issue_write_same fails and "mdXXX: > WRITE SAME failed. Manually zeroing" appear, but it's too late, > there aren't any disks left standing in the RAID. > > >I think the results of Tests 2 and 3 confirm that RAID10 definitely >needs to be fixed... Disabling WRITE SAME for RAID10 for now (3.10 + >stable) would be safest thing to do until this is sorted out properly. > >-- Joe -- Sent from my mobile phone. Please excuse brevity and lack of formatting. -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
