mke2fs
is used to create an ext2/ext3 filesystem (usually in a disk partition).
device
is the special file corresponding to the device (e.g
/dev/hdXX).
blocks-count
is the number of blocks on the device. If omitted,
mke2fs
automagically figures the file system size. If called as
mkfs.ext3
a journal is created as if the
-j
option was specified.
OPTIONS
-b block-size
Specify the size of blocks in bytes. Valid block size vales are 1024,
2048 and 4096 bytes per block. If omitted,
mke2fs
block-size is hueristically determined by the file system size and
the expected usage of the filesystem (see the
-T
option). If
block-size
is negative, then mke2fs will use hueristics to determine the
appropriate block size, with the constraint that the block size will be
at least
block-size
bytes. This is useful for certain hardware devices which require that
the blocksize be a multiple of 2k.
-c
Check the device for bad blocks before creating the file system. If
this option is specified twice, then a slower, destructive, read-write
test is used instead of a fast read-only test.
-f fragment-size
Specify the size of fragments in bytes.
-F
Force
mke2fs
to run, even if the specified device is not a
block special device, or appears to be mounted.
-g blocks-per-group
Specify the number of blocks in a block group. There is generally no
reason the user to ever set this parameter, as the default is optimal
for the filesystem. (For administrators who are creating
filesystems on RAID arrays, it is preferable to use the
stride
RAID parameter as part of the
-R
option rather than manipulating the number of blocks per group.)
This option is generally used by developers who
are developing test cases.
-i bytes-per-inode
Specify the bytes/inode ratio.
mke2fs
creates an inode for every
bytes-per-inode
bytes of space on the disk. The larger the
bytes-per-inode
ratio, the fewer inodes will be created. This value generally shouldn't
be smaller than the blocksize of the filesystem, since then too many
inodes will be made. Be warned that is not possible to expand the number
of inodes on a filesystem after it is created, so be careful deciding the
correct value for this parameter.
-j
Create the filesystem with an ext3 journal. 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.
-J journal-options
Create the ext3 journal using options specified on the command-line.
Journal options are comma
separated, and may take an argument using the equals ('=') sign.
The following journal options are supported:
size=journal-size
Create an internal journal (i.e., stored inside 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.
device=external-journal
Attach the filesystem to the journal block device located on
external-journal.
The external
journal must already have been created using the command
mke2fs -O journal_devexternal-journal
Note that
external-journal
must have been created with the
same block size as the new filesystem.
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 filename
Read the bad blocks list from
filename.
Note that the block numbers in the bad block list must be generated
using the same block size as used by mke2fs. As a result, the
-c
option to
mke2fs
is a much simpler and less error-prone method of checking a disk for bad
blocks before formatting it, as
mke2fs
will automatically pass the correct parameters to the
badblocks
program.
-L
Set the volume label for the filesystem.
-m reserved-blocks-percentage
Specify the percentage of the filesystem blocks reserved for
the super-user. This value defaults to 5%.
-M
Set the last mounted directory for the filesystem. This might be useful
for the sake of utilities that key off of the last mounted directory to
determine where the filesytem should be mounted.
-n
causes mke2fs to not actually create a filesystem, but display what it
would do if it were to create a filesystem. This can be used to
determine the location of the backup superblocks for a particular
filesystem, so long as the mke2fs parameters that were passed when the
filesystem was originally created are used again. (With the
-n
option added, of course!)
-N number-of-inodes
overrides the default calculation of the number of inodes that should be
reserved for the filesystem (which is based on the number of blocks and
the
bytes-per-inode
ratio). This allows the user to specify the number
of desired inodes directly.
-o creator-os
Manually override the default value of the "creator os" field of the
filesystem. Normally the creator field is set by default to the native OS
of the
mke2fs
executable.
-O feature[,...]
Create filesystem with given features (filesystem options). Features
which are normally turned on by default may be disabled by prefixing the
feature with a caret ('^') symbol.
Currently, the
sparse_super
and
filetype
features are turned on by default when
mke2fs
is run on a system with Linux 2.2 or later (unless creator-os is set to
the Hurd). Filesystems that may need to be mounted on pre-2.2 Linux or
other kernels should be created with
-O none
(or
-r 0
for Linux 1.2) which will disable these features, even if
mke2fs
is run on a system which can support them.
The following filesystem options are supported:
dir_index
Use hashed b-trees to speed up lookups in large directories.
filetype
Store file type information in directory entries.
has_journal
Create an ext3 journal (as if using the
-j
option).
journal_dev
Create an external ext3 journal on the given device
instead of a regular ext2 filesystem.
Note that
external-journal
must be created with the same
block size as the filesystems that will be using it.
sparse_super
Create a filesystem with fewer superblock backup copies
(saves space on large filesystems).
-q
Quiet execution. Useful if
mke2fs
is run in a script.
-r revision
Set the filesystem revision for the new filesystem. Note that 1.2
kernels only support revision 0 filesystems. The default is to
create revision 1 filesystems.
-R raid-options
Set raid-related options for the filesystem. Raid options are comma
separated, and may take an argument using the equals ('=') sign. The
following options are supported:
stride=stripe-size
Configure the filesystem for a RAID array with
stripe-size
filesystem blocks per stripe.
-S
Write superblock and group descriptors only. This is useful if all of
the superblock and backup superblocks are corrupted, and a last-ditch
recovery method is desired. It causes
mke2fs
to reinitialize the
superblock and group descriptors, while not touching the inode table
and the block and inode bitmaps. The
e2fsck
program should be run immediately after this option is used, and there
is no guarantee that any data will be salvageable. It is critical to
specify the correct filesystem blocksize when using this option,
or there is no chance of recovery.
-T fs-type
Specify how the filesystem is going to be used, so that mke2fs can
chose optimal filesystem parameters for that use. The supported
filesystem types are:
news
one inode per 4kb block
largefile
one inode per megabyte
largefile4
one inode per 4 megabytes
-v
Verbose execution.
-V
Print the version number of
mke2fs
and exit.
AUTHOR
This version of
mke2fs
has been written by Theodore Ts'o <tytso@mit.edu>.
BUGS
mke2fs
accepts the
-f
option but currently ignores it because the second
extended file system does not support fragments yet.
There may be other ones. Please, report them to the author.