mke2fs - Unix, Linux Command
NAME
mke2fs - create an ext2/ext3 filesystem
SYNOPSIS
mke2fs [
-c |
-l filename ]
[
-b block-size ]
[
-f fragment-size ]
[
-g blocks-per-group ]
[
-i bytes-per-inode ]
[
-j ]
[
-J journal-options ]
[
-N number-of-inodes ]
[
-n ]
[
-m reserved-blocks-percentage ]
[
-o creator-os ]
[
-O feature[,...] ]
[
-q ]
[
-r fs-revision-level ]
[
-E extended-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 specified.
OPTIONS
| Tag | Description |
|---|
|
-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 heuristically 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 heuristics 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, read-write
test is used instead of a fast read-only test.
|
|
-E extended-options |
| |
Set extended options for the filesystem. Extended options are comma
separated, and may take an argument using the equals (’=’) sign. The
-E option used to be
-R in earlier versions of
mke2fs. The
-R option is still accepted for backwards compatibility. The
following extended options are supported:
|
| Tag | Description |
|---|
| |
| Tag | Description |
|---|
|
stride=stripe-size | | |
Configure the filesystem for a RAID array with
stripe-size filesystem blocks per stripe.
|
|
resize=max-online-resize | | |
Reserve enough space so that the block group descriptor table can grow
to support a filesystem that has max-online-resize blocks.
|
|
|
-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:
|
| |
| Tag | Description |
|---|
|
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.
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 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 new-volume-label |
| |
Set the volume label for the filesystem to
new-volume-label. The maximum length of the
volume label is 16 bytes.
|
|
-m reserved-blocks-percentage |
| |
Specify the percentage of the filesystem blocks reserved for
the super-user. This avoids fragmentation, and allows root-owned
daemons, such as
syslogd(8),
to continue to function correctly after non-privileged processes are
prevented from writing to the filesystem. The default percentage
is 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 filesystem 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), overriding
the default filesystem options. The default features which are
enabled by default are specified by the
base_features relation, either in the
[libdefaults] section in the
/etc/mke2fs.conf configuration file, or in the subsection of the
[fs_types] section for the filesystem type as specified by the
-T option. The filesystem type-specific configuration setting found in
the
[fs_types] section will override the global default found in
[libdefaults].
The filesystem feature set will be further edited
using either the feature set specification specified by this option,
or if this option is not specified, by the
default_features relation for the filesystem type being created, or in the
[libdefaults] section of the configuration file.
The filesystem feature set is comprised of a list of features, separated
by commas, that are to be enabled. To disable a feature, simply
prefix the feature name with a caret (’^’) character. The
pseudo-filesystem feature "none" will clear all filesystem features.
|
| |
| Tag | Description |
|---|
|
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.
|
|
resize_inode | | |
Reserve space so the block group descriptor table may grow in the future.
Useful for online resizing using
resize2fs. By default
mke2fs will attempt to reserve enough space so that the
filesystem may grow to 1024 times its initial size. This can be changed
using
resize extended option.
|
|
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.
|
|
-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 choose optimal filesystem parameters for that use. The filesystem
types that are can be supported are defined in the configuration file
/etc/mke2fs.conf(5).
The default configuration file contains definitions for the filesystem
types: small, floppy, news, largefile, and largefile4.
|
|
-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.
AVAILABILITY
mke2fs is part of the e2fsprogs package and is available from
http://e2fsprogs.sourceforge.net.
SEE ALSO
|
