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. kvě 10.30 /dev/mapper/vg_test-lvol0 -> ../dm-0
[root@trim ~]# cat /sys/block/dm-0/queue/discard_zeroes_data
1
[root@trim ~]# uname -r
2.6.39-rc5-blkdev+
[root@trim ~]# cat /proc/partitions
8 19 1951897 sdb3
8 49 1951866 sdd1
253 0 3584000 dm-0
So I assume it got fixes just recently ?. I'll give it a try with the
up-to-date kernel.
Thanks!
-Lukas
