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... >>> >>> -- >>> twalberg@xxxxxxxxx, twalberg@xxxxxxxxxxx >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in >>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>> More majordomo info at http://vger.kernel.org/majordomo-info.html > End of included message > > > -- Jeff Mahoney SUSE Labs
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