fstrim(8)
NAME
fstrim - discard unused blocks on a mounted filesystem
SYNOPSIS
fstrim [-a] [-o offset] [-l length] [-m minimum-size] [-v] mountpoint
DESCRIPTION
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.
OPTIONS
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, --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 are
silently ignored.
-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.
-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. 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).
-V, --version
Display version information and exit.
-h, --help
Display help text and exit.
RETURN CODES
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).
AUTHOR
Lukas Czerner <lczerner@redhat.com> Karel Zak <kzak@redhat.com>
SEE ALSO
mount(8), blkdiscard(8)
AVAILABILITY
The fstrim command is part of the util-linux package and is available from ftp://ftp.kernel.org/pub/linux/utils/util-linux/.
Opportunity
Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.
Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.
Free Software
Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.
Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.
Free Books
The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.
Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.
Education
Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.
Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.
