From: Tim Walberg <twalberg@comcast.net>
To: linux-btrfs@vger.kernel.org
Subject: question re: trim in btrfs
Date: Tue, 18 Oct 2016 12:42:38 -0500 [thread overview]
Message-ID: <20161018174238.GB5559@comcast.net> (raw)
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@gmail.com, twalberg@comcast.net
next reply other threads:[~2016-10-18 17:42 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-18 17:42 Tim Walberg [this message]
2016-10-18 19:06 ` question re: trim in btrfs Tim Walberg
2016-10-18 21:31 ` Jeff Mahoney
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