Re: [dm-devel] do not disable ext4 discards on first discard failure? [was: Re: dm snapshot: ignore discards issued to the snapshot-origin target]

[Karel Zak <kzak redhat com>]

On Wed, May 04, 2011 at 11:16:05AM -0400, Martin K. Petersen wrote:
> >>>>> "Lukas" == Lukas Czerner <lczerner redhat com> writes:
> 
> I got tired of poking around in sysfs to find the discard topology.
> Here's a patch against lsblk that adds a -D option to present this
> information in a human-readable form:

Applied, thanks.

> # lsblk -D
> NAME                  DISC-ALN DISC-GRAN DISC-MAX DISC-ZERO
> sda                          0        0B       0B         0
> └─sda1                       0        0B       0B         0
> sdb                          0      512B       2G         1
> └─sdb1                       0      512B       2G         1

I have a question, 2.6.35 on my ThinkPad, non-SSD disk:

NAME                   DISC-ALN DISC-GRAN DISC-MAX DISC-ZERO
sda                           0        0B       0B         0
├─sda1               4294935040        0B       0B         0
├─sda2               4188038656        0B       0B         0
├─sda3               1346205184        0B       0B         0
├─sda4               3231165440        0B       0B         0
├─sda5               4188006400        0B       0B         0
│ └─kzak-home (dm-0)          0        0B       0B         0
└─sda6               2035725312        0B       0B         0


Does is make sense? The DISC-ALN is non-zero but DISC-GRAN is zero.

Note that cat /sys/block/sda/sda*/discard_alignment returns the same
numbers.

    Karel

-- 
 Karel Zak  <kzak redhat com>
 http://karelzak.blogspot.com