1FSTRIM(8) System Administration FSTRIM(8)
2
6 fstrim - discard unused blocks on a mounted filesystem
7
9 fstrim [-Aa] [-o offset] [-l length] [-m minimum-size] [-v mountpoint]
10
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.
22 Running fstrim frequently, or even using mount -o discard, might
24 negatively affect the lifetime of poor-quality SSD devices. For most
25 desktop and server systems a sufficient trimming frequency is once a
26 week. Note that not all devices support a queued trim, so each trim
27 command incurs a performance penalty on whatever else might be trying
28 to use the disk at the time.
29
31 The offset, length, and minimum-size arguments may be followed by the
32 multiplicative suffixes KiB (=1024), MiB (=1024*1024), and so on for
33 GiB, TiB, PiB, EiB, ZiB and YiB (the "iB" is optional, e.g., "K" has
34 the same meaning as "KiB") or the suffixes KB (=1000), MB (=1000*1000),
35 and so on for GB, TB, PB, EB, ZB and YB.
36 -A, --fstab
38 Trim all mounted filesystems mentioned in /etc/fstab on devices
39 that support the discard operation. The root filesystem is
40 determined from kernel command line if missing in the file. The
41 other supplied options, like --offset, --length and --minimum, are
42 applied to all these devices. Errors from filesystems that do not
43 support the discard operation, read-only devices and read-only
44 filesystems are silently ignored.
45 -a, --all
47 Trim all mounted filesystems on devices that support the discard
48 operation. The other supplied options, like --offset, --length and
49 --minimum, are applied to all these devices. Errors from
50 filesystems that do not support the discard operation, read-only
51 devices and read-only filesystems are silently ignored.
52 -n, --dry-run
54 This option does everything apart from actually call FITRIM ioctl.
55 -o, --offset offset
57 Byte offset in the filesystem from which to begin searching for
58 free blocks to discard. The default value is zero, starting at the
59 beginning of the filesystem.
60 -l, --length length
62 The number of bytes (after the starting point) to search for free
63 blocks to discard. If the specified value extends past the end of
64 the filesystem, fstrim will stop at the filesystem size boundary.
65 The default value extends to the end of the filesystem.
66 -I, --listed-in list
68 Specifies a colon-separated list of files in fstab or kernel
69 mountinfo format. All missing or empty files are silently ignored.
70 The evaluation of the list stops after first non-empty file. For
71 example:
72 --listed-in /etc/fstab:/proc/self/mountinfo.
74 -m, --minimum minimum-size
76 Minimum contiguous free range to discard, in bytes. (This value is
77 internally rounded up to a multiple of the filesystem block size.)
78 Free ranges smaller than this will be ignored and fstrim will
79 adjust the minimum if it’s smaller than the device’s minimum, and
80 report that (fstrim_range.minlen) back to userspace. By increasing
81 this value, the fstrim operation will complete more quickly for
82 filesystems with badly fragmented freespace, although not all
83 blocks will be discarded. The default value is zero, discarding
84 every free block.
85 -v, --verbose
87 Verbose execution. With this option fstrim will output the number
88 of bytes passed from the filesystem down the block stack to the
89 device for potential discard. This number is a maximum discard
90 amount from the storage device’s perspective, because FITRIM ioctl
91 called repeated will keep sending the same sectors for discard
92 repeatedly.
93 fstrim will report the same potential discard bytes each time, but
95 only sectors which had been written to between the discards would
96 actually be discarded by the storage device. Further, the kernel
97 block layer reserves the right to adjust the discard ranges to fit
98 raid stripe geometry, non-trim capable devices in a LVM setup, etc.
99 These reductions would not be reflected in fstrim_range.len (the
100 --length option).
101 --quiet-unsupported
103 Suppress error messages if trim operation (ioctl) is unsupported.
104 This option is meant to be used in systemd service file or in cron
105 scripts to hide warnings that are result of known problems, such as
106 NTFS driver reporting Bad file descriptor when device is mounted
107 read-only, or lack of file system support for ioctl FITRIM call.
108 This option also cleans exit status when unsupported filesystem
109 specified on fstrim command line.
110 -V, --version
112 Display version information and exit.
113 -h, --help
115 Display help text and exit.
116
118 0
119 success
120 1
122 failure
123 32
125 all failed
126 64
128 some filesystem discards have succeeded, some failed
129 The command fstrim --all returns 0 (all succeeded), 32 (all failed) or
131 64 (some failed, some succeeded).
132
134 Lukas Czerner <lczerner@redhat.com>, Karel Zak <kzak@redhat.com>
135
137 blkdiscard(8), mount(8)
138
140 For bug reports, use the issue tracker at
141 https://github.com/karelzak/util-linux/issues.
142
144 The fstrim command is part of the util-linux package which can be
145 downloaded from Linux Kernel Archive
146 <https://www.kernel.org/pub/linux/utils/util-linux/>.
147util-linux 2.37.2 2021-07-20 FSTRIM(8)