tune2fs
adjust tunable filesystem parameters on ext2/ext3/ext4 filesystems
see also :
debugfs - dumpe2fs - e2fsck - mke2fs
Synopsis
tune2fs
[ -l ] [ -c
max-mount-counts ] [ -e
errors-behavior ] [ -f ] [
-i interval-between-checks ] [
-j ] [ -J journal-options ]
[ -m reserved-blocks-percentage ] [
-o [^]mount-options[,...] ] [
-r reserved-blocks-count ] [
-s sparse-super-flag ] [ -u
user ] [ -g group ] [
-C mount-count ] [ -E
extended-options ] [ -L
volume-name ] [ -M
last-mounted-directory ] [ -O
[^]feature[,...] ] [ -Q
quota-options ] [ -T
time-last-checked ] [ -U UUID ]
device
add an example, a script, a trick and tips
examples
source
mkfs.ext4 $PART
tune2fs -i 0 -c 0 $PART
mkdir -p $MOUNT
mount -t ext4 $PART $MOUNT
echo "$PART $MOUNT ext4
defaults 0 0" >> /etc/fstab
source
mount_count=$(tune2fs -l
$root | grep "Mount
count" | cut -d: -f 2 | tr -d "
")
echo "Mount count:
$mount_count" >> /run/auto-fsck.log
fsck -a $root >> /run/auto-fsck.log
2>&1
tune2fs -C 0 $root >>
/run/auto-fsck.log
fi
exit 0
### Capital -L parameter will change the volume-label name:
$ sudo tune2fs -L myhome /dev/sda1 tune2fs 1.40.8 (13-Mar-2013)
### Disable file system integrity check:
$ sudo tune2fs -i 0 /dev/sda1
tune2fs 1.40.8 (13-Mar-2008)
### Display file system superblock information:
$ sudo tune2fs -l /dev/sdb1
By: Mohammad Bazouie
example added by Mohammad Bazouie
source
exit
fi
tune2fs -O extents,uninit_bg,dir_index $1
fsck -f $1
$EDITOR /etc/fstab
description
tune2fs
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 -l option to tune2fs(8)
program, or by using the dumpe2fs(8) program.
The
device specifier can either be a filename (i.e.,
/dev/sda1), or a LABEL or UUID specifier:
"LABEL=volume-name" or
"UUID=uuid". (i.e., LABEL=home or
UUID=e40486c6-84d5-4f2f-b99c-032281799c9d).
options
-c
max-mount-counts
Adjust the number of mounts
after which the filesystem will be checked by
e2fsck(8). If max-mount-counts is 0 or
-1, the number of times the filesystem is mounted will
be disregarded by e2fsck(8) and the kernel.
Staggering the
mount-counts at which filesystems are forcibly checked will
avoid all filesystems being checked at one time when using
journaled filesystems.
You should
strongly consider the consequences of disabling
mount-count-dependent checking entirely. Bad disk drives,
cables, memory, and kernel bugs could all corrupt a
filesystem without marking the filesystem dirty or in error.
If you are using journaling on your filesystem, your
filesystem will never be marked dirty, so it will not
normally be checked. A filesystem error detected by the
kernel will still force an fsck on the next reboot, but it
may already be too late to prevent data loss at that
point.
See also the
-i option for time-dependent checking.
-C
mount-count
Set the number of times the
filesystem has been mounted. If set to a greater value than
the max-mount-counts parameter set by the -c
option, e2fsck(8) will check the filesystem at the
next reboot.
-e
error-behavior
Change the behavior of the
kernel code when errors are detected. In all cases, a
filesystem error will cause e2fsck(8) to check the
filesystem on the next boot. error-behavior can be
one of the following:
continue
Continue normal execution.
remount-ro
Remount filesystem read-only.
panic
Cause a kernel panic.
-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:
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’.
mmp_update_interval=interval
Adjust the initial MMP update
interval to interval seconds. Specifying an
interval of 0 means to use the default interval. The
specified interval must be less than 300 seconds. Requires
that the mmp feature be enabled.
stride=stride-size
Configure the filesystem for a
RAID array with 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 mke2fs(2) time to
avoid placing them on a single disk, which can hurt the
performance. It may also be used by block allocator.
stripe_width=stripe-width
Configure the filesystem for a
RAID array with 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.
hash_alg=hash-alg
Set the default hash algorithm
used for filesystems with hashed b-tree directories. Valid
algorithms accepted are: legacy, half_md4, and
tea.
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 -o option,
mount_option_string is an arbitrary string with a
maximum length of 63 bytes, which is stored in the
superblock.
The ext4 file
system driver will first apply the bitmask-based default
options, and then parse the mount_option_string,
before parsing the mount options passed from the
mount(8) program.
This superblock
setting is only honored in 2.6.35+ kernels; and not at all
by the ext2 and ext3 file system drivers.
test_fs
Set a flag in the filesystem
superblock indicating that it may be mounted using
experimental kernel code, such as the ext4dev
filesystem.
^test_fs
Clear the test_fs flag,
indicating the filesystem should only be mounted using
production-level filesystem code.
-f
Force the tune2fs operation to complete even in the face
of errors. This option is useful when removing the
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.
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.
-g
group
Set the group which can use the
reserved filesystem blocks. The group parameter can
be a numerical gid or a group name. If a group name is
given, it is converted to a numerical gid before it is
stored in the superblock.
-i
interval-between-checks[d|m|w]
Adjust the maximal time between
two filesystem checks. No suffix or d will interpret
the number interval-between-checks as days, m
as months, and w as weeks. A value of zero will
disable the time-dependent checking.
It is strongly
recommended that either -c
(mount-count-dependent) or -i (time-dependent)
checking be enabled to force periodic full e2fsck(8)
checking of the filesystem. Failure to do so may lead to
filesystem corruption (due to bad disks, cables, memory, or
kernel bugs) going unnoticed, ultimately resulting in data
loss or corruption.
-j
Add an ext3 journal to the filesystem. If the
-J option is not specified, the default journal
parameters will be used to create 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.
If this option
is used to create a journal on a mounted filesystem, an
immutable file, .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, e2fsck(8) will automatically
move .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, e2fsck(8) must be run from a
rescue floppy in order to effect this transition.
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 /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.
-J
journal-options
Override the default ext3
journal parameters. Journal options are comma separated, and
may take an argument using the equals (’=’)
sign. The following journal options are supported:
size=journal-size
Create a journal stored in the
filesystem of size journal-size megabytes. The size
of the journal must be at least 1024 filesystem blocks
(i.e., 1MB if using 1k blocks, 4MB if using 4k blocks, etc.)
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.
device=external-journal
Attach the filesystem to the
journal block device located on external-journal. The
external journal must have been already created using the
command
mke2fs -O
journal_dev external-journal
Note that
external-journal must be formatted with the same
block size as filesystems which will be using it. In
addition, while there is support for attaching multiple
filesystems to a single external journal, the Linux kernel
and e2fsck(8) do not currently support shared
external journals yet.
Instead of
specifying a device name directly, external-journal
can also be specified by either LABEL=label or
UUID=UUID to locate the external journal by
either the volume label or UUID stored in the ext2
superblock at the start of the journal. Use
dumpe2fs(8) to display a journal device’s
volume label and UUID. See also the -L option of
tune2fs(8).
Only one of the
size or device options can be given for a
filesystem.
-l
List the contents of the filesystem superblock,
including the current values of the parameters that can be
set via this program.
-L
volume-label
Set the volume label of the
filesystem. Ext2 filesystem labels can be at most 16
characters long; if volume-label is longer than 16
characters, tune2fs will truncate it and print a
warning. The volume label can be used by mount(8),
fsck(8), and /etc/fstab(5) (and possibly
others) by specifying LABEL=volume_label
instead of a block special device name like
/dev/hda5.
-m
reserved-blocks-percentage
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
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%.
-M
last-mounted-directory
Set the last-mounted directory
for the filesystem.
-o
[^]mount-option[,...]
Set or clear the indicated
default mount options in the filesystem. Default mount
options can be overridden by mount options specified either
in /etc/fstab(5) or on the command line arguments to
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.
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.
The following
mount options can be set or cleared using
tune2fs:
debug
Enable debugging code for this filesystem.
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.
user_xattr
Enable user-specified extended
attributes.
acl
Enable Posix Access Control Lists.
uid16
Disables 32-bit UIDs and GIDs. This is for
interoperability with older kernels which only store and
expect 16-bit values.
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.
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.
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.
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.)
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.)
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.)
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.)
-O
[^]feature[,...]
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.
The following
filesystem features can be set or cleared using
tune2fs:
dir_index
Use hashed b-trees to speed up
lookups in large directories.
dir_nlink
Allow more than 65000
subdirectories per directory.
filetype
Store file type information in
directory entries.
flex_bg
Allow bitmaps and inode tables
for a block group to be placed anywhere on the storage
media. Tune2fs will not reorganize the location of
the inode tables and allocation bitmaps, as mke2fs(8)
will do when it creates a freshly formatted file system with
flex_bg enabled.
has_journal
Use a journal to ensure
filesystem consistency even across unclean shutdowns.
Setting the filesystem feature is equivalent to using the
-j option.
large_file
Filesystem can contain files
that are greater than 2GB. (Modern kernels set this feature
automatically when a file > 2GB is created.)
resize_inode
Reserve space so the block
group descriptor table may grow in the future.
Tune2fs only supports clearing this filesystem
feature.
mmp
Enable or disable multiple mount protection (MMP)
feature. MMP helps to protect the filesystem from being
multiply mounted and is useful in shared storage
environments.
sparse_super
Limit the number of backup
superblocks to save space on large filesystems.
uninit_bg
Allow the kernel to initialize
bitmaps and inode tables and keep a high watermark for the
unused inodes in a filesystem, to reduce 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.
After setting
or clearing sparse_super, uninit_bg,
filetype, or resize_inode filesystem features,
e2fsck(8) must be run on the filesystem to return the
filesystem to a consistent state. Tune2fs will print
a message requesting that the system administrator run
e2fsck(8) if necessary. After setting the
dir_index feature, 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 uninit_bg
and flex_bg features are only supported by the ext4
filesystem.
-p
mmp_check_interval
Set the desired MMP check
interval in seconds. It is 5 seconds by default.
-r
reserved-blocks-count
Set the number of reserved
filesystem blocks.
-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:
[^]usrquota
Sets/clears user quota inode in
the superblock.
[^]grpquota
Sets/clears group quota inode
in the superblock.
-T
time-last-checked
Set the time the filesystem was
last checked using 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 time-last-checked is the international date
format, with an optional time specifier, i.e.
YYYYMMDD[HH[MM[SS]]]. The keyword now is also
accepted, in which case the last checked time will be set to
the current time.
-u user
Set the user who can use the
reserved filesystem blocks. user can be a numerical
uid or a user name. If a user name is given, it is converted
to a numerical uid before it is stored in the
superblock.
-U UUID
Set the universally unique
identifier (UUID) of the filesystem to UUID. The
format of the UUID is a series of hex digits separated by
hyphens, like this:
"c1b9d5a2-f162-11cf-9ece-0020afc76f16". The
UUID parameter may also be one of the following:
clear
clear the filesystem UUID
random
generate a new randomly-generated UUID
time
generate a new time-based UUID
The UUID may be
used by mount(8), fsck(8), and
/etc/fstab(5) (and possibly others) by specifying
UUID=uuid instead of a block special device
name like /dev/hda1.
See
uuidgen(8) for more information. If the system does
not have a good random number generator such as
/dev/random or /dev/urandom, tune2fs
will automatically use a time-based UUID instead of a
randomly-generated UUID.
availability
tune2fs is part of the e2fsprogs package and is available
from http://e2fsprogs.sourceforge.net.
bugs
We
haven’t found any bugs yet. That doesn’t mean
there aren’t any...
see also
debugfs ,
dumpe2fs , e2fsck , mke2fs
author
tune2fs
was written by Remy Card <Remy.Card[:at:]linux[:dot:]org>. It is
currently being maintained by Theodore Ts’o
<tytso[:at:]alum.mit[:dot:]edu>. tune2fs uses the ext2fs
library written by Theodore Ts’o
<tytso[:at:]mit[:dot:]edu>. This manual page was written by
Christian Kuhtz <chk@data-hh.Hanse.DE>. Time-dependent
checking was added by Uwe Ohse <uwe[:at:]tirka.gun[:dot:]de>.