[CentOS] LVM thin volumes fstrim operation not supported

Wed Jan 20 03:37:36 UTC 2016
Tim Robinson <terobinson at gmail.com>

Looked into this further and it looks like a kernel bug. If I
downgraded the running kernel everything started working again. I've
reported here https://bugs.centos.org/view.php?id=10191 with some more
details.

Thanks

On 20 January 2016 at 11:36, Tim Robinson <terobinson at gmail.com> wrote:
> I still get the "the discard operation is not supported" fstrim error
> when the LVs are set to "nopassdown"
>
> Seems that when I use ext4 the fstrim reports that it worked but the
> LVs Data% does not decrease after the fstrim. xfs just throws the
> error.
>
> I've also been looking at the output of lsblk -D
>
> # lsblk -D
> NAME                  DISC-ALN DISC-GRAN DISC-MAX DISC-ZERO
> xvdb                         0        0B       0B         0
> ├─data-pool00_tmeta          0        0B       0B         0
> │ └─data-pool00-tpool        0        0B       0B         0
> │   ├─data-pool00            0        0B       0B         0
> │   └─data-data              0        0B       0B         0
> └─data-pool00_tdata          0        0B       0B         0
>   └─data-pool00-tpool        0        0B       0B         0
>     ├─data-pool00            0        0B       0B         0
>     └─data-data              0        0B       0B         0
>
> I expect the DISC-GRAN and DISC-MAX to be greater than 0B.
>
>
> On 20 January 2016 at 09:46, Chris Murphy <lists at colorremedies.com> wrote:
>> My guess? The passthrough  is causing the error when the command passes
>> through to the actual device, which doesn't support Trim.
>>
>> I don't know how it actually works, but you can try to poke it with this
>> stick: copy a large file to this LV. Check the LV with lvdisplay. Delete
>> the file. Fstrim. Lvdisplay. Now compare the two lvdisplay results.
>>
>> It should show the PEs used are less after fstrim.
>>
>>
>> Chris Murphy
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