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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXIT STATUS | AUTHORS | SEE ALSO | AVAILABILITY | COLOPHON |
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FSTRIM(8) System Administration FSTRIM(8)
fstrim - discard unused blocks on a mounted filesystem
fstrim [-Aa] [-o offset] [-l length] [-m minimum-size] [-v]
mountpoint
fstrim is used on a mounted filesystem to discard (or "trim")
blocks which are not in use by the filesystem. This is useful
for solid-state drives (SSDs) and thinly-provisioned storage.
By default, fstrim will discard all unused blocks in the
filesystem. Options may be used to modify this behavior based on
range or size, as explained below.
The mountpoint argument is the pathname of the directory where
the filesystem is mounted.
Running fstrim frequently, or even using mount -o discard, might
negatively affect the lifetime of poor-quality SSD devices. For
most desktop and server systems a sufficient trimming frequency
is once a week. Note that not all devices support a queued trim,
so each trim command incurs a performance penalty on whatever
else might be trying to use the disk at the time.
The offset, length, and minimum-size arguments may be followed by
the multiplicative suffixes KiB (=1024), MiB (=1024*1024), and so
on for GiB, TiB, PiB, EiB, ZiB and YiB (the "iB" is optional,
e.g., "K" has the same meaning as "KiB") or the suffixes KB
(=1000), MB (=1000*1000), and so on for GB, TB, PB, EB, ZB and
YB.
-A, --fstab
Trim all mounted filesystems mentioned in /etc/fstab on
devices that support the discard operation. The root
filesystem is determined from kernel command line if
missing in the file. The other supplied options, like
--offset, --length and --minimum, are applied to all these
devices. Errors from filesystems that do not support the
discard operation, read-only devices and read-only
filesystems are silently ignored.
-a, --all
Trim all mounted filesystems on devices that support the
discard operation. The other supplied options, like
--offset, --length and --minimum, are applied to all these
devices. Errors from filesystems that do not support the
discard operation, read-only devices and read-only
filesystems are silently ignored.
-n, --dry-run
This option does everything apart from actually call
FITRIM ioctl.
-o, --offset offset
Byte offset in the filesystem from which to begin
searching for free blocks to discard. The default value
is zero, starting at the beginning of the filesystem.
-l, --length length
The number of bytes (after the starting point) to search
for free blocks to discard. If the specified value
extends past the end of the filesystem, fstrim will stop
at the filesystem size boundary. The default value
extends to the end of the filesystem.
-I, --listed-in list
Specifies a colon-separated list of files in fstab or
kernel mountinfo format. All missing or empty files are
silently ignored. The evaluation of the list stops after
first non-empty file. For example: --listed-in
/etc/fstab:/proc/self/mountinfo.
-m, --minimum minimum-size
Minimum contiguous free range to discard, in bytes. (This
value is internally rounded up to a multiple of the
filesystem block size.) Free ranges smaller than this
will be ignored and fstrim will adjust the minimum if it's
smaller than the device's minimum, and report that
(fstrim_range.minlen) back to userspace. By increasing
this value, the fstrim operation will complete more
quickly for filesystems with badly fragmented freespace,
although not all blocks will be discarded. The default
value is zero, discarding every free block.
-v, --verbose
Verbose execution. With this option fstrim will output
the number of bytes passed from the filesystem down the
block stack to the device for potential discard. This
number is a maximum discard amount from the storage
device's perspective, because FITRIM ioctl called repeated
will keep sending the same sectors for discard repeatedly.
fstrim will report the same potential discard bytes each
time, but only sectors which had been written to between
the discards would actually be discarded by the storage
device. Further, the kernel block layer reserves the
right to adjust the discard ranges to fit raid stripe
geometry, non-trim capable devices in a LVM setup, etc.
These reductions would not be reflected in
fstrim_range.len (the --length option).
--quiet-unsupported
Suppress error messages if trim operation (ioctl) is
unsupported. This option is meant to be used in systemd
service file or in cron scripts to hide warnings that are
result of known problems, such as NTFS driver reporting
Bad file descriptor when device is mounted read-only, or
lack of file system support for ioctl FITRIM call.
-V, --version
Display version information and exit.
-h, --help
Display help text and exit.
0 success
1 failure
32 all failed
64 some filesystem discards have succeeded, some failed
The command fstrim --all returns 0 (all succeeded), 32 (all
failed) or 64 (some failed, some succeeded).
Lukas Czerner <lczerner@redhat.com>
Karel Zak <kzak@redhat.com>
blkdiscard(8), mount(8)
The fstrim command is part of the util-linux package and is
available from
https://www.kernel.org/pub/linux/utils/util-linux/.
This page is part of the util-linux (a random collection of Linux
utilities) project. Information about the project can be found
at ⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩. If you
have a bug report for this manual page, send it to
util-linux@vger.kernel.org. This page was obtained from the
project's upstream Git repository
⟨git://git.kernel.org/pub/scm/utils/util-linux/util-linux.git⟩ on
2020-12-18. (At that time, the date of the most recent commit
that was found in the repository was 2020-12-17.) If you
discover any rendering problems in this HTML version of the page,
or you believe there is a better or more up-to-date source for
the page, or you have corrections or improvements to the
information in this COLOPHON (which is not part of the original
manual page), send a mail to man-pages@man7.org
util-linux May 2019 FSTRIM(8)
Pages that refer to this page: blkdiscard(8)
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