1FSTRIM(8) System Administration FSTRIM(8)
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6 fstrim - discard unused blocks on a mounted filesystem
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9 fstrim [-Aav] [-o offset] [-l length] [-m minimum-size] [mountpoint]
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12 fstrim is used on a mounted filesystem to discard (or "trim") blocks
13 which are not in use by the filesystem. This is useful for solid-state
14 drives (SSDs) and thinly-provisioned storage.
15 By default, fstrim will discard all unused blocks in the filesystem.
17 Options may be used to modify this behavior based on range or size, as
18 explained below.
19 The mountpoint argument is the pathname of the directory where the
21 filesystem is mounted and is required when -A, -a, --fstab, or --all
22 are unspecified.
23 Running fstrim frequently, or even using mount -o discard, might
25 negatively affect the lifetime of poor-quality SSD devices. For most
26 desktop and server systems a sufficient trimming frequency is once a
27 week. Note that not all devices support a queued trim, so each trim
28 command incurs a performance penalty on whatever else might be trying
29 to use the disk at the time.
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32 The offset, length, and minimum-size arguments may be followed by the
33 multiplicative suffixes KiB (=1024), MiB (=1024*1024), and so on for
34 GiB, TiB, PiB, EiB, ZiB and YiB (the "iB" is optional, e.g., "K" has
35 the same meaning as "KiB") or the suffixes KB (=1000), MB (=1000*1000),
36 and so on for GB, TB, PB, EB, ZB and YB.
37 -A, --fstab
39 Trim all mounted filesystems mentioned in /etc/fstab on devices
40 that support the discard operation. The root filesystem is
41 determined from kernel command line if missing in the file. The
42 other supplied options, like --offset, --length and --minimum, are
43 applied to all these devices. Errors from filesystems that do not
44 support the discard operation, read-only devices, autofs and
45 read-only filesystems are silently ignored. Filesystems with
46 "X-fstrim.notrim" mount option are skipped.
47 -a, --all
49 Trim all mounted filesystems on devices that support the discard
50 operation. The other supplied options, like --offset, --length and
51 --minimum, are applied to all these devices. Errors from
52 filesystems that do not support the discard operation, read-only
53 devices and read-only filesystems are silently ignored.
54 -n, --dry-run
56 This option does everything apart from actually call FITRIM ioctl.
57 -o, --offset offset
59 Byte offset in the filesystem from which to begin searching for
60 free blocks to discard. The default value is zero, starting at the
61 beginning of the filesystem.
62 -l, --length length
64 The number of bytes (after the starting point) to search for free
65 blocks to discard. If the specified value extends past the end of
66 the filesystem, fstrim will stop at the filesystem size boundary.
67 The default value extends to the end of the filesystem.
68 -I, --listed-in list
70 Specifies a colon-separated list of files in fstab or kernel
71 mountinfo format. All missing or empty files are silently ignored.
72 The evaluation of the list stops after first non-empty file. For
73 example:
74 --listed-in /etc/fstab:/proc/self/mountinfo.
76 Filesystems with "X-fstrim.notrim" mount option in fstab are
78 skipped.
79 -m, --minimum minimum-size
81 Minimum contiguous free range to discard, in bytes. (This value is
82 internally rounded up to a multiple of the filesystem block size.)
83 Free ranges smaller than this will be ignored and fstrim will
84 adjust the minimum if it’s smaller than the device’s minimum, and
85 report that (fstrim_range.minlen) back to userspace. By increasing
86 this value, the fstrim operation will complete more quickly for
87 filesystems with badly fragmented freespace, although not all
88 blocks will be discarded. The default value is zero, discarding
89 every free block.
90 -t, --types list
92 Specifies allowed or forbidden filesystem types when used with
93 --all or --fstab. The list is a comma-separated list of the
94 filesystem names. The list follows how mount -t evaluates type
95 patterns. Only specified filesystem types are allowed. All
96 specified types are forbidden if the list is prefixed by "no" or
97 each filesystem prefixed by "no" is forbidden. If the option is not
98 used, then all filesystems (except "autofs") are allowed.
99 -v, --verbose
101 Verbose execution. With this option fstrim will output the number
102 of bytes passed from the filesystem down the block stack to the
103 device for potential discard. This number is a maximum discard
104 amount from the storage device’s perspective, because FITRIM ioctl
105 called repeated will keep sending the same sectors for discard
106 repeatedly.
107 fstrim will report the same potential discard bytes each time, but
109 only sectors which had been written to between the discards would
110 actually be discarded by the storage device. Further, the kernel
111 block layer reserves the right to adjust the discard ranges to fit
112 raid stripe geometry, non-trim capable devices in a LVM setup, etc.
113 These reductions would not be reflected in fstrim_range.len (the
114 --length option).
115 --quiet-unsupported
117 Suppress error messages if trim operation (ioctl) is unsupported.
118 This option is meant to be used in systemd service file or in
119 cron(8) scripts to hide warnings that are result of known problems,
120 such as NTFS driver reporting Bad file descriptor when device is
121 mounted read-only, or lack of file system support for ioctl FITRIM
122 call. This option also cleans exit status when unsupported
123 filesystem specified on fstrim command line.
124 -h, --help
126 Display help text and exit.
127 -V, --version
129 Print version and exit.
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132 0
133 success
134 1
136 failure
137 32
139 all failed
140 64
142 some filesystem discards have succeeded, some failed
143 The command fstrim --all returns 0 (all succeeded), 32 (all failed) or
145 64 (some failed, some succeeded).
146
148 Lukas Czerner <lczerner@redhat.com>, Karel Zak <kzak@redhat.com>
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151 blkdiscard(8), mount(8)
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154 For bug reports, use the issue tracker at
155 https://github.com/util-linux/util-linux/issues.
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158 The fstrim command is part of the util-linux package which can be
159 downloaded from Linux Kernel Archive
160 <https://www.kernel.org/pub/linux/utils/util-linux/>.
161util-linux 2.39.2 2023-06-14 FSTRIM(8)