mke2fs
MKE2FS(8) MKE2FS(8)
NAME
mke2fs - create an ext2/3 filesystem
SYNOPSIS
mke2fs [ -c | -l filename ] [ -b block-size ] [ -f fragment-size ] [ -i
bytes-per-inode ] [ -j ] [ -J journal-options ] [ -N number-of-inodes ]
[ -n ] [ -m reserved-blocks-percentage ] [ -o creator-os ] [ -O fea-
ture[,...] ] [ -q ] [ -r fs-revision-level ] [ -R raid-options ] [ -v
] [ -F ] [ -L volume-label ] [ -M last-mounted-directory ] [ -S ] [ -T
filesystem-type ] [ -V ] device [ blocks-count ]
mke2fs -O journal_dev [ -b block-size ] [ -L volume-label ] [ -n ] [ -q
] [ -v ] external-journal [ blocks-count ]
DESCRIPTION
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 speci-
fied.
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 determined by the file system size and the expected
usage of the filesystem (see the -T option).
-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.
-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 cor-
rect 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_dev external-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, exter-
nal-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 auto-
matically 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 fea-
tures, even if mke2fs is run on a system which can support them.
The following filesystem options are supported:
sparse_super
Create a filesystem with fewer superblock backup
copies (saves space on large filesystems).
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.
-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 salvage-
able. It is critical to specify the correct filesystem block-
size 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 sup-
ported 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 sec-
ond extended file system does not support fragments yet.
There may be other ones. Please, report them to the author.
AVAILABILITY
mke2fs is part of the e2fsprogs package and is available from
http://e2fsprogs.sourceforge.net.
SEE ALSO
badblocks(8), dumpe2fs(8), e2fsck(8), tune2fs(8)
E2fsprogs version 1.32 November 2002 MKE2FS(8)
