.\"
.TH TUNE2FS 8 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
.SH NAME
-tune2fs \- adjust tunable filesystem parameters on ext2/ext3 filesystems
+tune2fs \- adjust tunable filesystem parameters on ext2/ext3/ext4 filesystems
.SH SYNOPSIS
.B tune2fs
[
.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
]
.SH DESCRIPTION
.BI tune2fs
allows the system administrator to adjust various tunable filesystem
-parameters on Linux ext2/ext3 filesystems.
+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"
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
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.
+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
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
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@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.
Enable debugging code for this filesystem.
.TP
.B bsdgroups
-Emulate BSD behaviour when creating new files: they will take the group-id
-of the directory in which they were created. The standard System V behaviour
+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
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[,...]"
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 dir_index
-Use hashed b-trees to speed up lookups in large directories.
+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
Use a journal to ensure filesystem consistency even across unclean shutdowns.
Setting the filesystem feature is equivalent to using the
.B \-j
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
-.B sparse_super
-and
-.B filetype
+.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.
feature,
.B e2fsck -D
can be run to convert existing directories to the hashed B-tree format.
-.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.
+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
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