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From: Noah Massey <noah.massey@gmail.com>
To: linux-btrfs <linux-btrfs@vger.kernel.org>
Subject: fstrim on BTRFS
Date: Thu, 30 Oct 2014 20:21:17 -0400	[thread overview]
Message-ID: <CADfjVrj9dwq4gpzcFt_OW4wFb+oLX-cvD5PAOfnHTMqCzHfcvw@mail.gmail.com> (raw)

Hello,

I am looking for some clarification on TRIM / SSD maintenance.
The wiki [1] suggests periodic fstrim, but fstrim does not discard
unallocated blocks[2].
Which makes sense, given that mkfs issues a device wide trim, so they
shouldn't have data.

But it seems like both a balance, and a pending patch
( 47ab2a6 Btrfs: remove empty block groups automatically )
can deallocate block groups without TRIM, leading to the SSD retaining
data it doesn't need to.

Is there a bitter way to trigger a more thorough discard than
fallocate, rm, fstrim, balance -dusage=0 ?
And are there plans to support trimming unallocated space, or is this
not possible with current FS format?

Thank you,
Noah

[1] https://btrfs.wiki.kernel.org/index.php/FAQ#Does_Btrfs_support_TRIM.2Fdiscard.3F
[2] https://www.mail-archive.com/linux-btrfs@vger.kernel.org/msg14195.html

             reply	other threads:[~2014-10-31  0:21 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-10-31  0:21 Noah Massey [this message]
  -- strict thread matches above, loose matches on Subject: below --
2011-12-28 16:57 fstrim on BTRFS Martin Steigerwald
2011-12-29  4:02 ` Li Zefan
2011-12-29  4:21   ` Fajar A. Nugraha
2011-12-29  4:32     ` Fajar A. Nugraha
2011-12-29  4:37     ` Roman Mamedov
2011-12-29  4:42       ` Fajar A. Nugraha
2011-12-29  5:29         ` cwillu
2011-12-29 10:52   ` Martin Steigerwald
2012-01-03 21:05   ` Chris Mason
2011-12-29  4:29 ` Fajar A. Nugraha
2011-12-29  9:39   ` Li Zefan
2011-12-29  9:52     ` Fajar A. Nugraha
2011-12-30  6:19       ` Li Zefan
2011-12-30  6:35         ` Fajar A. Nugraha

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