[linux-lvm] [dm-devel] do not disable ext4 discards on first discard failure? [was: Re: dm snapshot: ignore discards issued to the snapshot-origin target]
Lukas Czerner
lczerner at redhat.com
Thu May 5 10:48:41 UTC 2011
On Thu, 5 May 2011, Karel Zak wrote:
> On Wed, May 04, 2011 at 11:16:05AM -0400, Martin K. Petersen wrote:
> > >>>>> "Lukas" == Lukas Czerner <lczerner at 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
>
>
That is fixed by the kernel patch posted above :)
-Lukas
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