.\" -*- 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 a Linux second extended file system
+mke2fs \- create an ext2/ext3 filesystem
.SH SYNOPSIS
.B mke2fs
[
.B \-c
-|
-.\" .B \-t
-.\" .I test
-.\" |
+|
.B \-l
.I filename
]
.I fragment-size
]
[
+.B \-g
+.I blocks-per-group
+]
+[
+.B \-G
+.I number-of-groups
+]
+[
.B \-i
.I bytes-per-inode
]
[
+.B \-I
+.I inode-size
+]
+[
+.B \-j
+]
+[
+.B \-J
+.I journal-options
+]
+[
.B \-N
.I number-of-inodes
]
[
-.B -n
+.B \-n
]
[
.B \-m
.I creator-os
]
[
-.B \-O
+.B \-O
.IR feature [,...]
]
[
.I fs-revision-level
]
[
-.B \-R
-.I raid_options
-]
-[
-.B \-s
-.I sparse-super-flag
+.B \-E
+.I extended-options
]
[
.B \-v
.B \-S
]
[
+.B \-t
+.I fs-type
+]
+[
.B \-T
-.I filesystem-type
+.I usage-type
+]
+[
+.B \-U
+.I UUID
]
[
.B \-V
[
.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 a Linux second extended file system on a device (usually
-a disk partition).
+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
+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.
+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,
+Specify the size of blocks in bytes. Valid block-size values 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
+block-size is heuristically determined by the filesystem size and
+the expected usage of the filesystem (see the
.B \-T
-option).
+option). If
+.I block-size
+is negative, then
+.B mke2fs
+will use heuristics to determine the
+appropriate block size, with the constraint that the block size will be
+at least
+.I block-size
+bytes. This is useful for certain hardware devices which require that
+the blocksize be a multiple of 2k.
.TP
.B \-c
-Check the device for bad blocks before creating the file system, using a
-fast read-only test.
+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.
+.TP
+.BI \-E " extended-options"
+Set extended options for the filesystem. Extended options are comma
+separated, and may take an argument using the equals ('=') sign. The
+.B \-E
+option used to be
+.B \-R
+in earlier versions of
+.BR mke2fs .
+The
+.B \-R
+option is still accepted for backwards compatibility. The
+following extended options are supported:
+.RS 1.2i
+.TP
+.BI stride= stride-size
+Configure the filesystem for a RAID array with
+.I stride-size
+filesystem blocks. This is the number of blocks read or written to disk
+before moving to the next disk, which is sometimes referred to as the
+.I chunk size.
+This mostly affects placement of filesystem metadata like bitmaps at
+.B mke2fs
+time to avoid placing them on a single disk, which can hurt performance.
+It may also be used by the block allocator.
+.TP
+.BI stripe-width= stripe-width
+Configure the filesystem for a RAID array with
+.I stripe-width
+filesystem blocks per stripe. This is typically stride-size * N, where
+N is the number of data-bearing disks in the RAID (e.g. for RAID 5 there is one
+parity disk, so N will be the number of disks in the array minus 1).
+This allows the block allocator to prevent read-modify-write of the
+parity in a RAID stripe if possible when the data is written.
+.TP
+.BI resize= max-online-resize
+Reserve enough space so that the block group descriptor table can grow
+to support a filesystem that has
+.I max-online-resize
+blocks.
+.TP
+.B lazy_itable_init\fR[\fB= \fI<0 to disable, 1 to enable>\fR]
+If enabled and the uninit_bg feature is enabled, the inode table will
+not be fully initialized by
+.BR mke2fs .
+This speeds up filesystem
+initialization noticeably, but it requires the kernel to finish
+initializing the filesystem in the background when the filesystem is
+first mounted. If the option value is omitted, it defaults to 1 to
+enable lazy inode table initialization.
+.TP
+.B test_fs
+Set a flag in the filesystem superblock indicating that it may be
+mounted using experimental kernel code, such as the ext4dev filesystem.
+.RE
.TP
.BI \-f " fragment-size"
Specify the size of fragments in bytes.
.TP
+.B \-F
+Force
+.B mke2fs
+to create a filesystem, even if the specified device is not a partition
+on a block special device, or if other parameters do not make sense.
+In order to force
+.B mke2fs
+to create a filesystem even if the filesystem appears to be in use
+or is mounted (a truly dangerous thing to do), this option must be
+specified twice.
+.TP
+.BI \-g " blocks-per-group"
+Specify the number of blocks in a block group. There is generally no
+reason for 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
+.I stride
+RAID parameter as part of the
+.B \-E
+option rather than manipulating the number of blocks per group.)
+This option is generally used by developers who
+are developing test cases.
+.TP
+.BI \-G " number-of-groups"
+Specify the number of block groups that will be packed together to
+create one large virtual block group on an ext4 filesystem. This
+improves meta-data locality and performance on meta-data heavy
+workloads. The number of groups must be a power of 2 and may only be
+specified if the flex_bg filesystem feature is enabled.
+.TP
.BI \-i " bytes-per-inode"
-Specify the bytes/inode ratio.
+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
+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 decided the correct
-value for this parameter.
+ratio, the fewer inodes will be created. This value generally shouldn't
+be smaller than the blocksize of the filesystem, since in that case more
+inodes would be made than can ever be used. Be warned that it 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
+.BI \-I " inode-size"
+Specify the size of each inode in bytes.
+.B mke2fs
+creates 256-byte inodes by default. In kernels after 2.6.10 and some
+earlier vendor kernels it is possible to utilize inodes larger than
+128 bytes to store
+extended attributes for improved performance. The
+.I inode-size
+value must be a power of 2 larger or equal to 128. The larger the
+.I inode-size
+the more space the inode table will consume, and this reduces the usable
+space in the filesystem and can also negatively impact performance.
+Extended attributes
+stored in large inodes are not visible with older kernels, and such
+filesystems will not be mountable with 2.4 kernels at all. It is not
+possible to change this value after the filesystem is created.
+.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@In addition, while there is support for attaching
+@JDEV@multiple filesystems to a single external journal,
+@JDEV@the Linux kernel and
+@JDEV@.BR e2fsck (8)
+@JDEV@do not currently support shared external journals yet.
+@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
+.BR 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
+.BI \-L " new-volume-label"
+Set the volume label for the filesystem to
+.IR new-volume-label .
+The maximum length of the
+volume label is 16 bytes.
+.TP
+.BI \-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
+.BR syslogd (8),
+to continue to function correctly after non-privileged processes are
+prevented from writing to the filesystem. The default percentage
+is 5%.
+.TP
+.BI \-M " last-mounted-directory"
+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.
.TP
.B \-n
-causes mke2fs to not actually create a filesystem, but display what it
-would do if it were to create a filesystem.
+Causes
+.B 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
+.B 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
+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
+ratio). This allows the user to specify the number
of desired inodes directly.
.TP
-.BI \-O " feature\fR[,...]"
-Create the filesystem with the listed set of features
-(filesystem options). The following features are supported:
-.IR sparse ,
-which cause the filesystem to use sparse superblocks, and
-.IR filetype ,
-which will cause the filesystem to store file type information in
-directory entries. Currently, both features are turned on by default
-unless
+.BI \-o " creator-os"
+Overrides the default value of the "creator operating system" field of the
+filesystem. The creator field is set by default to the name of the OS the
.B mke2fs
-is run on a system with a pre-2.2 Linux kernel.
-.B Warning:
-Pre-2.2 Linux kernels do not properly
-support the filesystems that use either of these two features. Filesystems
-that may need to mounted on pre-2.2 kernels should be created with
-.B -O
-.I none
-which will disable both of these features, even if
-.B mke2fs
-is run on a system which can support these features.
+executable was compiled for.
.TP
-.BI \-l " filename"
-Read the bad blocks list from
-.I filename.
-\.
+.B "\-O \fIfeature\fR[,...]"
+Create a filesystem with the given features (filesystem options),
+overriding the default filesystem options. The features that are
+enabled by default are specified by the
+.I base_features
+relation, either in the
+.I [defaults]
+section in the
+.B /etc/mke2fs.conf
+configuration file,
+or in the
+.I [fs_types]
+subsections for the usage types as specified by the
+.B \-T
+option, further modified by the
+.I features
+relation found in the
+.I [fs_types]
+subsections for the filesystem and usage types. See the
+.BR mke2fs.conf (5)
+manual page for more details.
+The filesystem type-specific configuration setting found in the
+.I [fs_types]
+section will override the global default found in
+.IR [defaults] .
+.sp
+The filesystem feature set will be further edited
+using either the feature set specified by this option,
+or if this option is not given, by the
+.I default_features
+relation for the filesystem type being created, or in the
+.I [defaults]
+section of the configuration file.
+.sp
+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.
+.RS 1.2i
.TP
-.BI -m " reserved-blocks-percentage"
-Specify the percentage of reserved blocks for the super-user. This value
-defaults to 5%.
-.\" .TP
-.\" .BI \-t " test"
-.\" Check the device for bad blocks before creating the file system
-.\" using the specified test.
+.B large_file
+Filesystem can contain files that are greater than 2GB. (Modern kernels
+set this feature automatically when a file > 2GB is created.)
.TP
-.B \-o
-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.
+.B dir_index
+Use hashed b-trees to speed up lookups in large directories.
.TP
-.B \-q
-Quiet execution. Useful if
-.B mke2fs
-is run in a script.
+.B filetype
+Store file type information in directory entries.
.TP
-.BI \-s " sparse-super-flag"
-If
-.I sparse-super-flag
-is 1, then turn on the sparse superblock flag in the superblock.
-.B Note:
-This option is deprecated; use the
-.B \-O
-option instead.
+.B flex_bg
+Allow bitmaps and inode tables for a block group to be placed anywhere
+on the storage media (use with \-G option to group meta-data in order
+to create a large virtual block group).
.TP
-.B \-v
-Verbose execution.
+.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 \-F
-Force
+.B extent
+Instead of using the indirect block scheme for storing the location of
+data blocks in an inode, use extents instead. This is a much more
+efficient encoding which speeds up filesystem access, especially for
+large files.
+.TP
+.B uninit_bg
+Create a filesystem without initializing all of the block groups. This
+feature also enables checksums and highest-inode-used statistics in each
+blockgroup. This feature can
+speed up filesystem creation time noticeably (if lazy_itable_init is
+enabled), and can also reduce
+.BR e2fsck
+time dramatically. It is only supported by the ext4 filesystem in
+recent Linux kernels.
+.TP
+.B resize_inode
+Reserve space so the block group descriptor table may grow in the future.
+Useful for online resizing using
+.BR resize2fs .
+By default
.B mke2fs
-to run, even if the specified device is not a
-block special device, or appears to be mounted.
+will attempt to reserve enough space so that the
+filesystem may grow to 1024 times its initial size. This can be changed
+using the
+.B resize
+extended option.
.TP
-.B \-L
-Set the volume label for the filesystem.
+.B sparse_super
+Create a filesystem with fewer superblock backup copies
+(saves space on large filesystems).
+.RE
.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.
+.B \-q
+Quiet execution. Useful if
+.B mke2fs
+is run in a script.
.TP
-.BI -r " revision"
+.BI \-r " revision"
Set the filesystem revision for the new filesystem. Note that 1.2
-kernels only support revision 0 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.
-Currently the only supported argument is
-.I stride
-which takes as its argument the number of blocks in a RAID stripe.
+kernels only support revision 0 filesystems. The default is to
+create revision 1 filesystems.
.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
+recovery method is desired. It causes
.B mke2fs
-to reinitialize the
+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.
+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 the filesystem type (i.e., ext2, ext3, ext4, etc.) that is to be created.
+If this option is not specified,
+.B mke2fs
+will pick a default either via how
+the command was run (for example, using a name of the form mkfs.ext2,
+mkfs.ext3, etc.) or via a default as defined by the
+.BR /etc/mke2fs.conf (5)
+file. This option controls which filesystem options are used by
+default, based on the
+.B fstypes
+configuration stanza in
+.BR /etc/mke2fs.conf (5).
+.sp
+If the
+.B \-O
+option is used to explicitly add or remove filesystem options that
+should be set in the newly created filesystem, the
+resulting filesystem may not be supported by the requested
+.IR fs-type .
+(e.g., "\fBmke2fs -t ext3 -O extents /dev/sdXX\fR" will create a
+filesystem that is not supported by the ext3 implementation as found in
+the Linux kernel; and "\fBmke2fs -t ext3 -O ^has_journal /dev/hdXX\fR"
+will create a filesystem that does not have a journal and hence will not
+be supported by the ext3 filesystem code in the Linux kernel.)
+.TP
+.BI \-T " usage-type[,...]"
+Specify how the filesystem is going to be used, so that
+.B mke2fs
+can choose optimal filesystem parameters for that use. The usage
+types that are supported are defined in the configuration file
+.BR /etc/mke2fs.conf (5).
+The user may specify one or more usage types
+using a comma separated list.
+.sp
+If this option is is not specified,
+.B mke2fs
+will pick a single default usage type based on the size of the filesystem to
+be created. If the filesystem size is less than or equal to 3 megabytes,
+.B mke2fs
+will use the filesystem type
+.IR floppy .
+If the filesystem size is greater than 3 but less than or equal to
+512 megabytes,
+.BR mke2fs (8)
+will use the filesystem
+.IR small .
+Otherwise,
+.BR mke2fs (8)
+will use the default filesystem type
+.IR default .
.TP
-.BI \-T " fs-type"
-Specify how the filesystem is going to be used, so that mke2fs can
-automatically determine the optimal filesystem parameters. The only
-filesystem type which is currently supported is "news".
+.BI \-U " UUID"
+Create the filesystem with the specified UUID.
+.TP
+.B \-v
+Verbose execution.
.TP
.B \-V
-Print the version number of
+Print the version number of
.B mke2fs
and exit.
.SH AUTHOR
option but currently ignores it because the second
extended file system does not support fragments yet.
.br
-There may be some other ones. Please, report them to the author.
+There may be other ones. Please, report them to the author.
.SH AVAILABILITY
.B mke2fs
-is part of the e2fsprogs package and is available for anonymous
-ftp from tsx-11.mit.edu in /pub/linux/packages/ext2fs.
+is part of the e2fsprogs package and is available from
+http://e2fsprogs.sourceforge.net.
.SH SEE ALSO
+.BR mke2fs.conf (5),
.BR badblocks (8),
.BR dumpe2fs (8),
.BR e2fsck (8),
git://git.whamcloud.com / tools / e2fsprogs.git / blobdiff