Fix bug where mke2fs was incorrectly checking

[thirdparty/e2fsprogs.git] / misc / mke2fs.8.in

.\" -*- nroff -*-
.\" Copyright 1993, 1994, 1995 by Theodore Ts'o.  All Rights Reserved.
.\" This file may be copied under the terms of the GNU Public License.
.\" 
.TH MKE2FS 8 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
.SH NAME
mke2fs \- create an ext2/3 filesystem
.SH SYNOPSIS
.B mke2fs
[
.B \-c
| 
.B \-l
.I filename
]
[
.B \-b
.I block-size
]
[
.B \-f
.I fragment-size
]
[
.B \-i
.I bytes-per-inode
]
[
.B \-j
]
[
.B \-J
.I journal-options
]
[
.B \-N
.I number-of-inodes
]
[
.B -n
]
[
.B \-m
.I reserved-blocks-percentage
]
[
.B \-o
.I creator-os
]
[
.B \-O 
.IR feature [,...]
]
[
.B \-q
]
[
.B \-r
.I fs-revision-level
]
[
.B \-R
.I raid-options
]
[
.B \-v
]
[
.B \-F
]
[
.B \-L
.I volume-label
]
[
.B \-M
.I last-mounted-directory
]
[
.B \-S
]
[
.B \-T
.I filesystem-type
]
[
.B \-V
]
.I device
[
.I blocks-count
]
@JDEV@.sp
@JDEV@.B "mke2fs \-O journal_dev"
@JDEV@[
@JDEV@.B \-b
@JDEV@.I block-size
@JDEV@]
.\" No external-journal specific journal options yet (size is ignored)
.\" @JDEV@[
.\" @JDEV@.B \-J
.\" @JDEV@.I journal-options
.\" @JDEV@]
@JDEV@[
@JDEV@.B \-L
@JDEV@.I volume-label
@JDEV@]
@JDEV@[
@JDEV@.B \-n
@JDEV@]
@JDEV@[
@JDEV@.B \-q
@JDEV@]
@JDEV@[
@JDEV@.B \-v
@JDEV@]
@JDEV@.I external-journal
@JDEV@[
@JDEV@.I blocks-count
@JDEV@]
.SH DESCRIPTION
.B mke2fs
is used to create an ext2/ext3 filesystem (usually in a disk partition).
.I device
is the special file corresponding to the device (e.g 
.IR /dev/hdXX ).
.I blocks-count
is the number of blocks on the device.  If omitted,
.B mke2fs
automagically figures the file system size.  If called as
.B mkfs.ext3
a journal is created as if the
.B \-j
option was specified.
.SH OPTIONS
.TP
.BI \-b " block-size"
Specify the size of blocks in bytes.  Valid block size vales are 1024, 
2048 and 4096 bytes per block.  If omitted,
.B mke2fs
block-size is determined by the file system size and the expected usage
of the filesystem (see the
.B \-T
option).
.TP
.B \-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.
.TP
.BI \-f " fragment-size"
Specify the size of fragments in bytes.
.TP
.B \-F
Force 
.B mke2fs
to run, even if the specified device is not a 
block special device, or appears to be mounted.
.TP
.BI \-i " bytes-per-inode"
Specify the bytes/inode ratio. 
.B mke2fs
creates an inode for every
.I bytes-per-inode
bytes of space on the disk.  The larger the 
.I 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. 
.TP 
.B \-j
Create the filesystem with an ext3 journal.  If the
.B \-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.
.TP
.BI \-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:
.RS 1.2i
.TP
.BI size= journal-size
Create an internal journal (i.e., stored inside the filesystem) of size
.I 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.  
@JDEV@.TP
@JDEV@.BI device= external-journal
@JDEV@Attach the filesystem to the journal block device located on
@JDEV@.IR external-journal .
@JDEV@The external
@JDEV@journal must already have been created using the command
@JDEV@.IP
@JDEV@.B mke2fs -O journal_dev
@JDEV@.I external-journal
@JDEV@.IP
@JDEV@Note that
@JDEV@.I external-journal
@JDEV@must have been created with the
@JDEV@same block size as the new filesystem.
@JDEV@.IP
@JDEV@Instead of specifying a device name directly,
@JDEV@.I external-journal
@JDEV@can also be specified by either
@JDEV@.BI LABEL= label
@JDEV@or
@JDEV@.BI UUID= UUID
@JDEV@to locate the external journal by either the volume label or UUID
@JDEV@stored in the ext2 superblock at the start of the journal.  Use
@JDEV@.BR dumpe2fs (8)
@JDEV@to display a journal device's volume label and UUID.  See also the
@JDEV@.B -L
@JDEV@option of
@JDEV@.BR tune2fs (8).
.RE
@JDEV@.IP
@JDEV@Only one of the
@JDEV@.BR size " or " device
@JDEV@options can be given for a filesystem.
.TP
.BI \-l " filename"
Read the bad blocks list from
.IR 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
.B \-c
option to 
.B mke2fs
is a much simpler and less error-prone method of checking a disk for bad
blocks before formatting it, as 
.B mke2fs
will automatically pass the correct parameters to the
.B badblocks
program.
.TP
.B \-L
Set the volume label for the filesystem.
.TP
.BI \-m " reserved-blocks-percentage"
Specify the percentage of the filesystem blocks reserved for 
the super-user.  This value defaults to 5%.
.TP
.B \-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.
.TP
.B \-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
.B \-n 
option added, of course!)
.TP
.BI \-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 
.I bytes-per-inode
ratio).  This allows the user to specify the number 
of desired inodes directly.
.TP
.BI \-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
.B mke2fs
executable.
.TP
.B "\-O \fIfeature\fR[,...]"
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
.B sparse_super
and
.B filetype
features are turned on by default when 
.B 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
.B "\-O none"
(or
.B "\-r 0"
for Linux 1.2) which will disable these features, even if 
.B mke2fs 
is run on a system which can support them.
.sp
The following filesystem options are supported:
.RS 1.2i
.TP
.B dir_index
Use hashed b-trees to speed up lookups in large directories.
.TP
.B filetype
Store file type information in directory entries.
.TP
.B has_journal
Create an ext3 journal (as if using the
.B \-j
option).
@JDEV@.TP
@JDEV@.B journal_dev
@JDEV@Create an external ext3 journal on the given device
@JDEV@instead of a regular ext2 filesystem.
@JDEV@Note that
@JDEV@.I external-journal
@JDEV@must be created with the same
@JDEV@block size as the filesystems that will be using it.
.TP
.B sparse_super
Create a filesystem with fewer superblock backup copies
(saves space on large filesystems).
.RE
.TP
.B \-q
Quiet execution.  Useful if 
.B mke2fs
is run in a script.
.TP
.BI \-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.
.TP
.BI \-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:
.RS 1.2i
.TP
.BI stride= stripe-size
Configure the filesystem for a RAID array with
.I stripe-size
filesystem blocks per stripe.
.RE
.TP
.B \-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 
.B mke2fs
to reinitialize the 
superblock and group descriptors, while not touching the inode table
and the block and inode bitmaps.  The
.B 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.
.\" .TP
.\" .BI \-t " test"
.\" Check the device for bad blocks before creating the file system
.\" using the specified test.
.TP
.BI \-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:
.RS 1.2i
.TP 1.2i
news
one inode per 4kb block
.TP
largefile
one inode per megabyte
.TP
largefile4
one inode per 4 megabytes
.RE
.TP
.B \-v
Verbose execution.
.TP
.B \-V
Print the version number of 
.B mke2fs
and exit.
.SH AUTHOR
This version of
.B mke2fs
has been written by Theodore Ts'o <tytso@mit.edu>.
.SH BUGS
.B mke2fs
accepts the
.B \-f
option but currently ignores it because the second
extended file system does not support fragments yet.
.br
There may be other ones.  Please, report them to the author.
.SH AVAILABILITY
.B mke2fs
is part of the e2fsprogs package and is available from 
http://e2fsprogs.sourceforge.net.
.SH SEE ALSO
.BR badblocks (8),
.BR dumpe2fs (8),
.BR e2fsck (8),
.BR tune2fs (8)