.\"
.TH TUNE2FS 8 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
.SH NAME
-tune2fs \- adjust tunable filesystem parameters on second extended filesystems
+tune2fs \- adjust tunable filesystem parameters on ext2/ext3/ext4 filesystems
.SH SYNOPSIS
.B tune2fs
[
.I errors-behavior
]
[
+.B \-f
+]
+[
.B \-i
.I interval-between-checks
]
.I reserved-blocks-percentage
]
[
+.B \-o
+.RI [^]mount-options [,...]
+]
+[
.B \-r
.I reserved-blocks-count
]
.I mount-count
]
[
+.B \-E
+.I extended-options
+]
+[
.B \-L
.I volume-name
]
.RI [^] feature [,...]
]
[
+.B \-Q
+.I quota-options
+]
+[
+.B \-T
+.I time-last-checked
+]
+[
.B \-U
.I UUID
]
device
.SH DESCRIPTION
.BI tune2fs
-adjusts tunable filesystem parameters on a Linux second extended filesystem.
+allows the system administrator to adjust various tunable filesystem
+parameters on Linux ext2, ext3, or ext4 filesystems. The current values
+of these options can be displayed by using the
+.B -l
+option to
+.BR tune2fs (8)
+program, or by using the
+.BR dumpe2fs (8)
+program.
+.PP
+The
+.I device
+specifier can either be a filename (i.e., /dev/sda1), or a LABEL or UUID
+specifier: "\fBLABEL=\fIvolume-name\fR" or "\fBUUID=\fIuuid\fR". (i.e.,
+LABEL=home or UUID=e40486c6-84d5-4f2f-b99c-032281799c9d).
.SH OPTIONS
.TP
.BI \-c " max-mount-counts"
-Adjust the maximal mounts count between two filesystem checks. If
+Adjust the number of mounts after which the filesystem will be checked by
+.BR e2fsck (8).
+If
.I max-mount-counts
-is 0 then the number of times the filesystem is mounted will be disregarded
+is 0 or \-1, the number of times the filesystem is mounted will be disregarded
by
.BR e2fsck (8)
and the kernel.
.TP
.BI \-C " mount-count"
Set the number of times the filesystem has been mounted.
-Can be used in conjunction with -c to force an fsck on
-the filesystem at the next reboot.
+If set to a greater value than the max-mount-counts parameter
+set by the
+.B \-c
+option,
+.BR e2fsck (8)
+will check the filesystem at the next reboot.
.TP
.BI \-e " error-behavior"
Change the behavior of the kernel code when errors are detected.
Cause a kernel panic.
.RE
.TP
+.BI \-E " extended-options"
+Set extended options for the filesystem. Extended options are comma
+separated, and may take an argument using the equals ('=') sign.
+The following extended options are supported:
+.RS 1.2i
+.TP
+.B clear_mmp
+Reset the MMP block (if any) back to the clean state. Use only if
+absolutely certain the device is not currently mounted or being
+fscked, or major filesystem corruption can result. Needs '-f'.
+.TP
+.BI mmp_update_interval= interval
+Adjust the initial MMP update interval to
+.I interval
+seconds. Specifying an
+.I interval
+of 0 means to use the default interval. The specified interval must
+be less than 300 seconds. Requires that the
+.B mmp
+feature be enabled.
+.TP
+.BI stride= stride-size
+Configure the filesystem for a RAID array with
+.I stride-size
+filesystem blocks. This is the number of blocks read or written to disk
+before moving to next disk. This mostly affects placement of filesystem
+metadata like bitmaps at
+.BR mke2fs (2)
+time to avoid placing them on a single disk, which can hurt the performance.
+It may also be used by block allocator.
+.TP
+.BI stripe_width= stripe-width
+Configure the filesystem for a RAID array with
+.I stripe-width
+filesystem blocks per stripe. This is typically be stride-size * N, where
+N is the number of data disks in the RAID (e.g. RAID 5 N+1, RAID 6 N+2).
+This allows the block allocator to prevent read-modify-write of the
+parity in a RAID stripe if possible when the data is written.
+.TP
+.BI hash_alg= hash-alg
+Set the default hash algorithm used for filesystems with hashed b-tree
+directories. Valid algorithms accepted are:
+.IR legacy ,
+.IR half_md4 ,
+and
+.IR tea .
+.TP
+.BI mount_opts= mount_option_string
+Set a set of default mount options which will be used when the file
+system is mounted. Unlike the bitmask-based default mount options which
+can be specified with the
+.B -o
+option,
+.I mount_option_string
+is an arbitrary string with a maximum length of 63 bytes, which is
+stored in the superblock.
+.IP
+The ext4 file system driver will first apply
+the bitmask-based default options, and then parse the
+.IR mount_option_string ,
+before parsing the mount options passed from the
+.BR mount (8)
+program.
+.IP
+This superblock setting is only honored in 2.6.35+ kernels;
+and not at all by the ext2 and ext3 file system drivers.
+.TP
+.B test_fs
+Set a flag in the filesystem superblock indicating that it may be
+mounted using experimental kernel code, such as the ext4dev filesystem.
+.TP
+.B ^test_fs
+Clear the test_fs flag, indicating the filesystem should only be mounted
+using production-level filesystem code.
+.RE
+.TP
+.B \-f
+Force the tune2fs operation to complete even in the face of errors. This
+option is useful when removing the
+.B has_journal
+filesystem feature from a filesystem which has
+an external journal (or is corrupted
+such that it appears to have an external journal), but that
+external journal is not available. If the filesystem appears to require
+journal replay, the
+.B \-f
+flag must be specified twice to proceed.
+.sp
+.B WARNING:
+Removing an external journal from a filesystem which was not cleanly unmounted
+without first replaying the external journal can result in
+severe data loss and filesystem corruption.
+.TP
.BI \-g " group"
-Set the group which can use reserved filesystem blocks.
+Set the group which can use the reserved filesystem blocks.
The
.I group
parameter can be a numerical gid or a group name. If a group name is given,
.TP
.B \-i " \fIinterval-between-checks\fR[\fBd\fR|\fBm\fR|\fBw\fR]"
Adjust the maximal time between two filesystem checks.
-No postfix or
+No suffix or
.B d
-result in days,
+will interpret the number
+.I interval-between-checks
+as days,
.B m
-in months, and
+as months, and
.B w
-in weeks. A value of zero will disable the time-dependent checking.
+as weeks. A value of zero will disable the time-dependent checking.
.sp
It is strongly recommended that either
.B \-c
(time-dependent) checking be enabled to force periodic full
.BR e2fsck (8)
checking of the filesystem. Failure to do so may lead to filesystem
-corruption due to bad disks, cables, memory, or kernel bugs to go
-unnoticed until they cause data loss or corruption.
+corruption (due to bad disks, cables, memory, or kernel bugs) going
+unnoticed, ultimately resulting in data loss or corruption.
.TP
.B \-j
Add an ext3 journal to the filesystem. If the
an appropriately sized journal (given the size of the filesystem)
stored within the filesystem. Note that you must be using a kernel
which has ext3 support in order to actually make use of the journal.
+.IP
+If this option is used to create a journal on a mounted filesystem, an
+immutable file,
+.BR .journal ,
+will be created in the top-level directory of the filesystem, as it is
+the only safe way to create the journal inode while the filesystem is
+mounted. While the ext3 journal is visible, it is not safe to
+delete it, or modify it while the filesystem is mounted; for this
+reason the file is marked immutable.
+While checking unmounted filesystems,
+.BR e2fsck (8)
+will automatically move
+.B .journal
+files to the invisible, reserved journal inode. For all filesystems
+except for the root filesystem, this should happen automatically and
+naturally during the next reboot cycle. Since the root filesystem is
+mounted read-only,
+.BR e2fsck (8)
+must be run from a rescue floppy in order to effect this transition.
+.IP
+On some distributions, such as Debian, if an initial ramdisk is used,
+the initrd scripts will automatically convert an ext2 root filesystem
+to ext3 if the
+.BR /etc/fstab
+file specifies the ext3 filesystem for the root filesystem in order to
+avoid requiring the use of a rescue floppy to add an ext3 journal to
+the root filesystem.
.TP
.BR \-J " journal-options"
Override the default ext3 journal parameters. Journal options are comma
and may be no more than 102,400 filesystem blocks.
There must be enough free space in the filesystem to create a journal of
that size.
+.TP
+.BI location =journal-location
+Specify the location of the journal. The argument
+.I journal-location
+can either be specified as a block number, or if the number has a units
+suffix (e.g., 'M', 'G', etc.) interpret it as the offset from the
+beginning of the file system.
@JDEV@.TP
@JDEV@.BI device= external-journal
@JDEV@Attach the filesystem to the journal block device located on
@JDEV@.I external-journal
@JDEV@must be formatted with the same block
@JDEV@size as filesystems which will be using it.
+@JDEV@In addition, while there is support for attaching
+@JDEV@multiple filesystems to a single external journal,
+@JDEV@the Linux kernel and
+@JDEV@.BR e2fsck (8)
+@JDEV@do not currently support shared external journals yet.
@JDEV@.IP
@JDEV@Instead of specifying a device name directly,
@JDEV@.I external-journal
@JDEV@options can be given for a filesystem.
.TP
.B \-l
-List the contents of the filesystem superblock.
+List the contents of the filesystem superblock, including the current
+values of the parameters that can be set via this program.
.TP
.BI \-L " volume-label"
Set the volume label of the filesystem.
.BR /dev/hda5 .
.TP
.BI \-m " reserved-blocks-percentage"
-Set the percentage of reserved filesystem blocks.
+Set the percentage of the filesystem which may only be allocated
+by privileged processes. Reserving some number of filesystem blocks
+for use by privileged processes is done
+to avoid filesystem fragmentation, and to allow system
+daemons, such as
+.BR syslogd (8),
+to continue to function correctly after non-privileged processes are
+prevented from writing to the filesystem. Normally, the default percentage
+of reserved blocks is 5%.
.TP
.BI \-M " last-mounted-directory"
Set the last-mounted directory for the filesystem.
.TP
+.BR \-o " [^]\fImount-option\fR[,...]"
+Set or clear the indicated default mount options in the filesystem.
+Default mount options can be overridden by mount options specified
+either in
+.BR /etc/fstab (5)
+or on the command line arguments to
+.BR mount (8).
+Older kernels may not support this feature; in particular,
+kernels which predate 2.4.20 will almost certainly ignore the
+default mount options field in the superblock.
+.IP
+More than one mount option can be cleared or set by separating
+features with commas. Mount options prefixed with a
+caret character ('^') will be cleared in the filesystem's superblock;
+mount options without a prefix character or prefixed with a plus
+character ('+') will be added to the filesystem.
+.IP
+The following mount options can be set or cleared using
+.BR tune2fs :
+.RS 1.2i
+.TP
+.B debug
+Enable debugging code for this filesystem.
+.TP
+.B bsdgroups
+Emulate BSD behavior when creating new files: they will take the group-id
+of the directory in which they were created. The standard System V behavior
+is the default, where newly created files take on the fsgid of the current
+process, unless the directory has the setgid bit set, in which case it takes
+the gid from the parent directory, and also gets the setgid bit set if it is
+a directory itself.
+.TP
+.B user_xattr
+Enable user-specified extended attributes.
+.TP
+.B acl
+Enable Posix Access Control Lists.
+.TP
+.B uid16
+Disables 32-bit UIDs and GIDs. This is for interoperability with
+older kernels which only store and expect 16-bit values.
+.TP
+.B journal_data
+When the filesystem is mounted with journalling enabled, all data
+(not just metadata) is committed into the journal prior to being written
+into the main filesystem.
+.TP
+.B journal_data_ordered
+When the filesystem is mounted with journalling enabled, all data is forced
+directly out to the main file system prior to its metadata being committed
+to the journal.
+.TP
+.B journal_data_writeback
+When the filesystem is mounted with journalling enabled, data may be
+written into the main filesystem after its metadata has been committed
+to the journal. This may increase throughput, however, it may allow old
+data to appear in files after a crash and journal recovery.
+.TP
+.B nobarrier
+The file system will be mounted with barrier operations in the journal
+disabled. (This option is currently only supported by the ext4 file
+system driver in 2.6.35+ kernels.)
+.TP
+.B block_validity
+The file system will be mounted with the block_validity option enabled,
+which causes extra checks to be performed after reading or writing from
+the file system. This prevents corrupted metadata blocks from causing
+file system damage by overwriting parts of the inode table or block
+group descriptors. This comes at the cost of increased memory and CPU
+overhead, so it is enabled only for debugging purposes. (This option is
+currently only supported by the ext4 file system driver in 2.6.35+
+kernels.)
+.TP
+.B discard
+The file system will be mounted with the discard mount option. This will
+cause the file system driver to attempt to use the trim/discard feature
+of some storage devices (such as SSD's and thin-provisioned drives
+available in some enterprise storage arrays) to inform the storage
+device that blocks belonging to deleted files can be reused for other
+purposes. (This option is currently only supported by the ext4 file
+system driver in 2.6.35+ kernels.)
+.TP
+.B nodelalloc
+The file system will be mounted with the nodelalloc mount option. This
+will disable the delayed allocation feature. (This option is currently
+only supported by the ext4 file system driver in 2.6.35+ kernels.)
+.RE
+.TP
.BR \-O " [^]\fIfeature\fR[,...]"
Set or clear the indicated filesystem features (options) in the filesystem.
More than one filesystem feature can be cleared or set by separating
features with commas. Filesystem features prefixed with a
caret character ('^') will be cleared in the filesystem's superblock;
filesystem features without a prefix character or prefixed with a plus
-character ('+') will be added to the filesystem.
+character ('+') will be added to the filesystem. For a detailed
+description of the file system features, please see the man page
+.BR ext4 (5).
.IP
The following filesystem features can be set or cleared using
.BR tune2fs :
.RS 1.2i
.TP
-.B sparse_super
-Limit the number of backup superblocks to save space on large filesystems.
+.B dir_index
+Use hashed b-trees to speed up lookups for large directories.
+.TP
+.B dir_nlink
+Allow more than 65000 subdirectories per directory.
+.TP
+.B extent
+Enable the use of extent trees to store the location of data blocks in inodes.
+.TP
+.B extra_isize
+Enable the extended inode fields used by ext4.
.TP
.B filetype
Store file type information in directory entries.
.TP
+.B flex_bg
+Allow bitmaps and inode tables for a block group to be placed
+anywhere on the storage media. \fBTune2fs\fR will not reorganize
+the location of the inode tables and allocation bitmaps, as
+.BR mke2fs (8)
+will do when it creates a freshly formatted file system with
+.B flex_bg
+enabled.
+.TP
.B has_journal
-Create an ext3 journal (as if using the
+Use a journal to ensure filesystem consistency even across unclean shutdowns.
+Setting the filesystem feature is equivalent to using the
.B \-j
-option).
+option.
+.TP
+.B huge_file
+Support files larger than 2 terabytes in size.
+.TP
+.B large_file
+Filesystem can contain files that are greater than 2GB.
+.TP
+.B resize_inode
+Reserve space so the block group descriptor table may grow in the
+future.
+.B Tune2fs
+only supports clearing this filesystem feature.
+.TP
+.B mmp
+Enable or disable multiple mount protection (MMP) feature.
+@QUOTA_MAN_COMMENT@.TP
+@QUOTA_MAN_COMMENT@.B quota
+@QUOTA_MAN_COMMENT@Enable internal file system quota inodes.
+.TP
+.B sparse_super
+Limit the number of backup superblocks to save space on large filesystems.
+.TP
+.B uninit_bg
+Allow the kernel to initialize bitmaps and inode tables lazily, and to
+keep a high watermark for the unused inodes in a filesystem, to reduce
+.BR e2fsck (8)
+time. This first e2fsck run after enabling this feature will take the
+full time, but subsequent e2fsck runs will take only a fraction of the
+original time, depending on how full the file system is.
.RE
.IP
-After setting or clearing any filesystem feature,
+After setting or clearing
+.BR sparse_super ,
+.BR uninit_bg ,
+.BR filetype ,
+or
+.B resize_inode
+filesystem features,
.BR e2fsck (8)
must be run on the filesystem to return the filesystem to a consistent state.
-.IP
-.B Warning:
-Linux kernels before 2.0.39 and many 2.1 series kernels do not support
-the filesystems that use any of these features.
-Enabling certain filesystem features may prevent the filesystem from
-being mounted by kernels which do not support those features.
+.B Tune2fs
+will print a message requesting that the system administrator run
+.BR e2fsck (8)
+if necessary. After setting the
+.B dir_index
+feature,
+.B e2fsck -D
+can be run to convert existing directories to the hashed B-tree format.
+Enabling certain filesystem features may prevent the filesystem from being
+mounted by kernels which do not support those features. In particular, the
+.BR uninit_bg
+and
+.BR flex_bg
+features are only supported by the ext4 filesystem.
+.TP
+.BI \-p " mmp_check_interval"
+Set the desired MMP check interval in seconds. It is 5 seconds by default.
.TP
.BI \-r " reserved-blocks-count"
Set the number of reserved filesystem blocks.
.TP
-.BR \-s " [" 0 | 1 ]
-Turn the sparse super feature off or on. Turning this feature on
-saves space on really big filesystems. This is the same as using the
-.B "\-O sparse_super"
-option.
-.IP
-.B Warning:
-Linux kernels before 2.0.39 do not support this feature. Neither do
-all Linux 2.1 kernels; please don't use this unless you know what you're
-doing! You need to run
-.BR e2fsck (8)
-on the filesystem after changing this feature in order to have a valid
-filesystem.
+.BI \-Q " quota-options"
+Sets 'quota' feature on the superblock and works on the quota files for the
+given quota type. Quota options could be one or more of the following:
+.RS 1.2i
+.TP
+.BR [^]usrquota
+Sets/clears user quota inode in the superblock.
+.TP
+.BR [^]grpquota
+Sets/clears group quota inode in the superblock.
+.RE
+.TP
+.BI \-T " time-last-checked"
+Set the time the filesystem was last checked using
+.BR e2fsck .
+The time is interpreted using the current (local) timezone.
+This can be useful in scripts which use a Logical Volume Manager to make
+a consistent snapshot of a filesystem, and then check the filesystem
+during off hours to make sure it hasn't been corrupted due to
+hardware problems, etc. If the filesystem was clean, then this option can
+be used to set the last checked time on the original filesystem. The format
+of
+.I time-last-checked
+is the international date format, with an optional time specifier, i.e.
+YYYYMMDD[HH[MM[SS]]]. The keyword
+.B now
+is also accepted, in which case the last checked time will be set to the
+current time.
.TP
.BI \-u " user"
Set the user who can use the reserved filesystem blocks.
.BI \-U " UUID"
Set the universally unique identifier (UUID) of the filesystem to
.IR UUID .
-The format of the UUID is a series of hex digits separated by hypthens,
+The format of the UUID is a series of hex digits separated by hyphens,
like this:
"c1b9d5a2-f162-11cf-9ece-0020afc76f16".
The
We haven't found any bugs yet. That doesn't mean there aren't any...
.SH AUTHOR
.B tune2fs
-was written by Remy Card <Remy.Card@linux.org>.
+was written by Remy Card <Remy.Card@linux.org>. It is currently being
+maintained by Theodore Ts'o <tytso@alum.mit.edu>.
.B tune2fs
uses the ext2fs library written by Theodore Ts'o <tytso@mit.edu>.
This manual page was written by Christian Kuhtz <chk@data-hh.Hanse.DE>.
is part of the e2fsprogs package and is available from
http://e2fsprogs.sourceforge.net.
.SH SEE ALSO
+.BR debugfs (8),
.BR dumpe2fs (8),
.BR e2fsck (8),
-.BR mke2fs (8)
+.BR mke2fs (8),
+.BR ext4 (5)
git://git.whamcloud.com / tools / e2fsprogs.git / blobdiff