.\"
.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
[
.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
]
[
.I fs-revision-level
]
[
-.B \-R
-.I raid-options
+.B \-E
+.I extended-options
]
[
.B \-v
.B \-S
]
[
+.B \-t
+.I fs-type
+]
+[
.B \-T
-.I filesystem-type
+.I usage-type
]
[
.B \-V
.I blocks-count
]
@JDEV@.sp
-@JDEV@.B "mke2fs \-O journal-dev"
+@JDEV@.B "mke2fs \-O journal_dev"
@JDEV@[
@JDEV@.B \-b
@JDEV@.I block-size
@JDEV@]
-.\" No journal-device specific journal options yet (size is ignored)
+.\" No external-journal specific journal options yet (size is ignored)
.\" @JDEV@[
.\" @JDEV@.B \-J
.\" @JDEV@.I journal-options
@JDEV@[
@JDEV@.B \-v
@JDEV@]
-@JDEV@.I journal-device
+@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
.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,
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 file system 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 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 the performanace.
+It may also be used by 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 be 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 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 fully initialized by
+.BR mke2fs .
+This speeds up filesystem
+initialization noitceably, 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.
.B \-F
Force
.B mke2fs
-to run, even if the specified device is not a
-block special device, or appears to be mounted.
+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 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 goups 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 goups 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.
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
+.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 two 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
.RS 1.2i
.TP
.BI size= journal-size
-Create a journal stored in the filesystem of size
-.IR 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 10,240 filesystem blocks.
-The journal must fit within the newly created filesystem.
+and may be no more than 102,400 filesystem blocks.
@JDEV@.TP
@JDEV@.BI device= external-journal
-@JDEV@Add an external journal found on a block device named by
-@JDEV@.I external-journal
-@JDEV@to the filesystem. The external
-@JDEV@journal must have been already created using the command
-@JDEV@.sp
-@JDEV@.B mke2fs \-O journal-dev
-@JDEV@.IR journal\-device
-@JDEV@.sp
+@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.
-.RE
.TP
.BI \-l " filename"
Read the bad blocks list from
-.IR filename .
+.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.
+.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 value defaults to 5%.
-.\" .TP
-.\" .BI \-t " test"
-.\" Check the device for bad blocks before creating the file system
-.\" using the specified test.
+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
.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.
+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 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
.B mke2fs
executable.
.TP
-.B \-O "\fIfeature\fR[,...]"
-Create filesystem with given features (filesystem options).
-Currently, the
-.B sparse_super
-and
-.B filetype
-features are turned on by default unless
-.B mke2fs
-is run on a system with a pre-2.2 Linux kernel.
+.B "\-O \fIfeature\fR[,...]"
+Create filesystem with given features (filesystem options), overriding
+the default filesystem options. The default features which are
+enabled by default are specified by the
+.I base_features
+relation, either in the
+.I [libdefaults]
+section in the
+.B /etc/mke2fs.conf
+configuration file,
+or in the subsection of the
+.I [fs_types]
+section for the usage types as specified by the
+.B -T
+option, further modified by the
+.I features
+relation found in the
+.I [fs_types] section
+based on 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 [libdefaults] .
.sp
-.B Warning:
-Linux kernels before 2.0.39 and many 2.1 series kernels do not support
-filesystems that use any of these features. Filesystems that
-may need to mounted on pre-2.2 kernels should be created with the
-.B "\-O none"
-(or
-.B "\-r 0"
-for 1.2 kernels) which will disable these features, even if
-.B mke2fs
-is run on a system which can support them.
+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
+.I default_features
+relation for the filesystem type being created, or in the
+.I [libdefaults]
+section of the configuration file.
.sp
-The following filesystem options are supported:
+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
-.B sparse_super
-Create a filesystem with fewer superblock backup copies
-(saves space on large filesystems).
+.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 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 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 has_journal
Create an ext3 journal (as if using the
.B \-j
option).
@JDEV@.TP
-@JDEV@.B journal-dev
+@JDEV@.B journal_dev
@JDEV@Create an external ext3 journal on the given device
-@JDEV@instead of a regular ext2 filesystem. The external ext3
-@JDEV@journal can be shared by multiple ext2 filesystems.
-.RE
+@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
-.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.
+.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
-.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
+.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 noticably (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
-.BI stride= stripe-size
-Configure the filesystem for a RAID array with
-.I strip-size
-filesystem blocks per stripe.
+.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
+will attempt to reserve enough space so that the
+filesystem may grow to 1024 times its initial size. This can be changed
+using
+.B resize
+extended option.
+.TP
+.B sparse_super
+Create a filesystem with fewer superblock backup copies
+(saves space on large filesystems).
.RE
.TP
.B \-q
.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
.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
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
+.BI
+.BI \-t " fs-type"
+Specify the filesystem (i.e., ext2, ext3, ext4, etc., is to be created.
+If this option is not specified mke2fs will pick a default either how
+the command was run (if it was run 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.
.TP
-largefile4
-one inode per 4 megabytes
-.RE
+.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
.B \-v
Verbose execution.
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 anonymous
+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