On 10/18/16 3:06 PM, Tim Walberg wrote:
> Forgot to mention - this was on a rather crusty 4.2.6 kernel. Just upgraded
> to 4.8.1
> and the issue appears to have been resolved...
Thanks for following up. This issue was actually fixed in v4.3. There
were a bunch of fixes for discard ranging from correct(ish[1]) reporting
of bytes discarded, discarding ranges in freed block groups, and missing
discards when using -odiscard.
-Jeff
[1] We report the range for which we issue discards. We don't track if
a particular range has been previously discarded.
> On 10/18/2016 12:42 -0500, Walberg, Tim wrote:
>>> Unless I'm misinterpreting something it appears that maybe btrfs
>>> doesn't pass
>>> fstrim commands down to the underlying drives when being used in a
>>> RAID-1 config.
>>>
>>> I have this output from a small script I wrote to run at boot time (and
>>> also via
>>> cron.weekly), rather than using continous trim in the boot options:
>>>
>>> # cat /var/log/trim.log
>>> Thu Oct 13 07:40:07 CDT 2016
>>> /boot: 454 MiB (476062720 bytes) trimmed
>>>
>>> Thu Oct 13 07:40:08 CDT 2016
>>> /: 8.9 GiB (9585152000 bytes) trimmed
>>>
>>> Thu Oct 13 07:40:22 CDT 2016
>>> /btrfs/0: 0 B (0 bytes) trimmed
>>>
>>> /boot and / are mdraid RAID 1 on partitions 1 and 3 of two Samsung 850
>>> Pro SSDs.
>>> /btrfs/0 is a btrfs-raid RAID 1 of partition 4 on the same two drives.
>>> The btrfs
>>> case does not seem to accomplish anything. By comparison, I have the
>>> same drive
>>> in my laptop, but just a single one, and the non-btrfs-raid-1 file
>>> system on one
>>> of its partitions does run fstrim successfully.
>>>
>>> This is quite possibly a known limitation, but I didn't find anything
>>> about it
>>> through some quick searching. Maybe I didn't dive deep enough...
>>>
>>> --
>>> twalb...@gmail.com, twalb...@comcast.net
>>> --
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> End of included message
>
>
>
--
Jeff Mahoney
SUSE Labs
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