On Mon, May 02 2011 at 10:39am -0400, Lukas Czerner <lczerner@xxxxxxxxxx> wrote: > On Mon, 2 May 2011, Martin K. Petersen wrote: > > > >>>>> "Lukas" == Lukas Czerner <lczerner@xxxxxxxxxx> writes: > > > > Lukas> So I gave it a try. First of all the device composed of SSD and > > Lukas> spinning disk does export discard_support information properly, > > Lukas> however it also advertise discard_zeroes_data which is wrong and > > Lukas> possibly dangerous and should be fixed! > > > > I can't reproduce this here. If I mix discard and non-discard devices > > things work correctly. discard_zeroes_data also gets cleared if I mix > > discard-capable drives where one zeroes and one doesn't. > > > > > > [root@trim ~]# hdparm -I /dev/sdb | grep -i trim > [root@trim ~]# cat /sys/block/sdb/queue/discard_zeroes_data > 0 > [root@trim ~]# hdparm -I /dev/sdd | grep -i trim > * Data Set Management TRIM supported > * Deterministic read after TRIM > [root@trim ~]# cat /sys/block/sdd/queue/discard_zeroes_data > 1 > [root@trim ~]# pvcreate /dev/sdd1 > Physical volume "/dev/sdd1" successfully created > [root@trim ~]# pvcreate /dev/sdb3 > Physical volume "/dev/sdb3" successfully created > [root@trim ~]# vgcreate vg_test /dev/sdd1 /dev/sdb3 > Volume group "vg_test" successfully created > [root@trim ~]# lvcreate -L 3500M vg_test > Logical volume "lvol0" created > [root@trim ~]# ls -lah /dev/mapper/vg_test-lvol0 > lrwxrwxrwx. 1 root root 7 2.ÂkvÄ 10.30 /dev/mapper/vg_test-lvol0 -> ../dm-0 > [root@trim ~]# cat /sys/block/dm-0/queue/discard_zeroes_data > 1 Hmm, Strange considering DM just uses blk_stack_limits(). As Martin said, current blk_stack_limits() code is fine: t->discard_zeroes_data &= b->discard_zeroes_data; > So I assume it got fixes just recently ?. I'll give it a try with the > up-to-date kernel. Hasn't changed at all since it was introduced: 98262f2 v2.6.33-rc1 block: Allow devices to indicate whether discarded blocks are zeroed -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
