.I block-size
]
[
-.B \-f
-.I fragment-size
+.B \-C
+.I cluster-size
+]
+[
+.B \-d
+.I root-directory
+]
+[
+.B \-D
]
[
.B \-g
]
[
.B \-O
-.IR feature [,...]
+[^]\fIfeature\fR[,...]
]
[
.B \-q
[
.B \-V
]
+[
+.B \-e
+.I errors-behavior
+]
+[
+.B \-z
+.I undo_file
+]
.I device
[
-.I blocks-count
+.I fs-size
]
@JDEV@.sp
@JDEV@.B "mke2fs \-O journal_dev"
@JDEV@]
@JDEV@.I external-journal
@JDEV@[
-@JDEV@.I blocks-count
+@JDEV@.I fs-size
@JDEV@]
.SH DESCRIPTION
.B mke2fs
is used to create an ext2, ext3, or ext4 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,
+partition (or file) named by
+.IR device .
+.PP
+The file system size is specified by
+.IR fs-size .
+If
+.I fs-size
+does not have a suffix, it is interpreted as power-of-two kilobytes,
+unless the
+.B \-b
+.I blocksize
+option is specified, in which case
+.I fs-size
+is interpreted as the number of
+.I blocksize
+blocks. If the fs-size is suffixed by 'k', 'm', 'g', 't'
+(either upper-case or lower-case), then it is interpreted in
+power-of-two kilobytes, megabytes, gigabytes, terabytes, etc.
+If
+.I fs-size
+is omitted,
+.B mke2fs
+will create the file system based on the device size.
+.PP
+If
.B mke2fs
-automagically figures the file system size. If called as
+is run as
+.B mkfs.XXX
+(i.e.,
+.BR mkfs.ext2 ,
+.BR mkfs.ext3 ,
+or
+.BR mkfs.ext4 )
+the option
+.B \-t
+.I XXX
+is implied; so
.B mkfs.ext3
-a journal is created as if the
-.B \-j
-option was specified.
+will create a file system for use with ext3,
+.B mkfs.ext4
+will create a file system for use with ext4, and so on.
.PP
The defaults of the parameters for the newly created filesystem, if not
overridden by the options listed below, are controlled by the
this option is specified twice, then a slower read-write
test is used instead of a fast read-only test.
.TP
+.B \-C " cluster-size"
+Specify the size of cluster in bytes for filesystems using the bigalloc
+feature. Valid cluster-size values are from 2048 to 256M bytes per
+cluster. This can only be specified if the bigalloc feature is
+enabled. (See the
+.B ext4 (5)
+man page for more details about bigalloc.) The default cluster size if
+bigalloc is enabled is 16 times the block size.
+.TP
+.BI \-d " root-directory"
+Copy the contents of the given directory into the root directory of the
+filesystem.
+.TP
+.B \-D
+Use direct I/O when writing to the disk. This avoids mke2fs dirtying a
+lot of buffer cache memory, which may impact other applications running
+on a busy server. This option will cause mke2fs to run much more
+slowly, however, so there is a tradeoff to using direct I/O.
+.TP
+.BI \-e " error-behavior"
+Change the behavior of the kernel code when errors are detected.
+In all cases, a filesystem error will cause
+.BR e2fsck (8)
+to check the filesystem on the next boot.
+.I error-behavior
+can be one of the following:
+.RS 1.2i
+.TP 1.2i
+.B continue
+Continue normal execution.
+.TP
+.B remount-ro
+Remount filesystem read-only.
+.TP
+.B panic
+Cause a kernel panic.
+.RE
+.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
.BR mke2fs .
The
.B \-R
-option is still accepted for backwards compatibility. The
-following extended options are supported:
+option is still accepted for backwards compatibility, but is deprecated.
+The following extended options are supported:
.RS 1.2i
.TP
+.BI fname_encoding= encoding-name
+Enable the
+.I fname_encoding
+feature in the super block and set
+.I encoding-name
+as the encoding to be used. If
+.I encoding-name
+is not specified, the encoding defined in
+.BR mke2fs.conf (5)
+is used.
+.TP
+.BI fname_encoding_flags= encoding-flags
+Define parameters for file name character encoding operations. If a
+flag is not changed using this parameter, its default value is used.
+.I encoding-flags
+should be a comma-separated lists of flags to be enabled. To disable a
+flag, add it to the list with the prefix "no".
+
+The only flag that can be set right now is
+.I strict
+which means that invalid strings should be rejected by the file system.
+In the default configuration, the
+.I strict
+flag is disabled.
+.TP
.BI mmp_update_interval= interval
Adjust the initial MMP update interval to
.I interval
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 offset= offset
+Create the filesystem at an offset from the beginning of the device or
+file. This can be useful when creating disk images for virtual machines.
+.TP
.BI resize= max-online-resize
Reserve enough space so that the block group descriptor table can grow
to support a filesystem that has
entirely one time. If the option value is omitted, it defaults to 1 to
enable lazy journal inode zeroing.
.TP
+.BI no_copy_xattrs
+Normally
+.B mke2fs
+will copy the extended attributes of the files in the directory
+hierarchy specified via the (optional)
+.B \-d
+option. This will disable the copy and leaves the files in the newly
+created file system without any extended attributes.
+.TP
+.BI num_backup_sb= <0|1|2>
+If the
+.B sparse_super2
+file system feature is enabled this option controls whether there will
+be 0, 1, or 2 backup superblocks created in the file system.
+.TP
+.B packed_meta_blocks\fR[\fB= \fI<0 to disable, 1 to enable>\fR]
+Place the allocation bitmaps and the inode table at the beginning of the
+disk. This option requires that the flex_bg file system feature to be
+enabled in order for it to have effect, and will also create the journal
+at the beginning of the file system. This option is useful for flash
+devices that use SLC flash at the beginning of the disk.
+It also maximizes the range of contiguous data blocks, which
+can be useful for certain specialized use cases, such as supported
+Shingled Drives.
+.TP
+.BI root_owner [=uid:gid]
+Specify the numeric user and group ID of the root directory. If no UID:GID
+is specified, use the user and group ID of the user running \fBmke2fs\fR.
+In \fBmke2fs\fR 1.42 and earlier the UID and GID of the root directory were
+set by default to the UID and GID of the user running the mke2fs command.
+The \fBroot_owner=\fR option allows explicitly specifying these values,
+and avoid side-effects for users that do not expect the contents of the
+filesystem to change based on the user running \fBmke2fs\fR.
+.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.
.TP
.BI nodiscard
Do not attempt to discard blocks at mkfs time.
-.RE
.TP
-.BI \-f " fragment-size"
-Specify the size of fragments in bytes.
+.BI quotatype
+Specify the which quota types (usrquota, grpquota, prjquota) which
+should be enabled in the created file system. The argument of this
+extended option should be a colon separated list. This option has
+effect only if the
+.B quota
+feature is set. The default quota types to be initialized if this
+option is not specified is both user and group quotas. If the project
+feature is enabled that project quotas will be initialized as well.
+.RE
.TP
.B \-F
Force
option rather than manipulating the number of blocks per group.)
This option is generally used by developers who
are developing test cases.
+.IP
+If the bigalloc feature is enabled, the
+.B \-g
+option will specify the number of clusters in a block group.
.TP
.BI \-G " number-of-groups"
Specify the number of block groups that will be packed together to
create a larger virtual block group (or "flex_bg group") in 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
+of 2 and may only be specified if the
.B flex_bg
filesystem feature is enabled.
.TP
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.
+possible to change this ratio on a filesystem after it is created, so be
+careful deciding the correct value for this parameter. Note that resizing
+a filesystem changes the number of inodes to maintain this ratio.
.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
+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.
+It is not
+possible to change this value after the filesystem is created.
+.IP
+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.
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.
+filesystems will not be mountable with 2.4 kernels at all.
+.IP
+The default inode size is controlled by the
+.BR mke2fs.conf (5)
+file. In the
+.B mke2fs.conf
+file shipped with e2fsprogs, the default inode size is 256 bytes for
+most file systems, except for small file systems where the inode size
+will be 128 bytes.
.TP
.B \-j
Create the filesystem with an ext3 journal. If the
(i.e., 1MB if using 1k blocks, 4MB if using 4k blocks, etc.)
and may be no more than 10,240,000 filesystem blocks or half the total
file system size (whichever is smaller)
+.TP
+.BI location =journal-location
+Specify the location of the journal. The argument
+.I journal-location
+can either be specified as a block number, or if the number has a units
+suffix (e.g., 'M', 'G', etc.) interpret it as the offset from the
+beginning of the file system.
@JDEV@.TP
@JDEV@.BI device= external-journal
@JDEV@Attach the filesystem to the journal block device located on
.B mke2fs
executable was compiled for.
.TP
-.B "\-O \fIfeature\fR[,...]"
+.B "\-O \fR[^]\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
.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
-.B dir_index
-Use hashed b-trees to speed up lookups in large directories.
-.TP
-.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 filetype
-Store file type information in directory entries.
-.TP
-.B flex_bg
-Allow the per-block group metadata (allocation bitmaps and inode tables)
-to be placed anywhere on the storage media. In addition,
-.B mke2fs
-will place the per-block group metadata together starting at the first
-block group of each "flex_bg group". The size of the flex_bg group
-can be specified using the
-.B \-G
-option.
-.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 large_file
-Filesystem can contain files that are greater than 2GB. (Modern kernels
-set this feature automatically when a file > 2GB is created.)
+prefix the feature name with a caret ('^') character.
+Features with dependencies will not be removed successfully.
+The pseudo-filesystem feature "none" will clear all filesystem features.
.TP
-.B quota
-Create quota inodes (inode# 3 for userquota and inode# 4 for group quota) and
-set them in the superblock. With this feature, the quotas will be enabled
-automatically when the filesystem is mounted.
-.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
-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 sparse_super
-Create a filesystem with fewer superblock backup copies
-(saves space on large filesystems).
-.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.
-.RE
+For more information about the features which can be set, please see
+the manual page
+.BR ext4 (5).
.TP
.B \-q
Quiet execution. Useful if
create revision 1 filesystems.
.TP
.B \-S
-Write superblock and group descriptors only. This is useful if all of
+Write superblock and group descriptors only. This is an extreme
+measure to be taken only in the very unlikely case that all of
the superblock and backup superblocks are corrupted, and a last-ditch
-recovery method is desired. It causes
+recovery method is desired by experienced users. It causes
.B mke2fs
-to reinitialize the
-superblock and group descriptors, while not touching the inode table
-and the block and inode bitmaps. 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. It is critical to
-specify the correct filesystem blocksize when using this option,
-or there is no chance of recovery.
+is no guarantee that any data will be salvageable. Due to the wide
+variety of possible options to
+.BR mke2fs
+that affect the on-disk layout, it is critical to specify exactly
+the same format options, such as blocksize, fs-type, feature flags, and
+other tunables when using this option, or the filesystem will be further
+corrupted. In some cases, such as filesystems that have been resized,
+or have had features enabled after format time, it is impossible to
+overwrite all of the superblocks correctly, and at least some filesystem
+corruption will occur. It is best to run this on a full copy of the
+filesystem so other options can be tried if this doesn't work.
.\" .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.
+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)
+.B /etc/mke2fs.conf
file. This option controls which filesystem options are used by
default, based on the
.B fstypes
configuration stanza in
-.BR /etc/mke2fs.conf (5).
+.BR /etc/mke2fs.conf .
.sp
If the
.B \-O
.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).
+.BR /etc/mke2fs.conf .
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,
+be created. If the filesystem size is less than 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
+If the filesystem size is greater than or equal to 3 but less than
512 megabytes,
.BR mke2fs (8)
will use the filesystem type
.IR default .
.TP
.BI \-U " UUID"
-Create the filesystem with the specified UUID.
+Set the universally unique identifier (UUID) of the filesystem to
+.IR UUID .
+The format of the UUID is a series of hex digits separated by hyphens,
+like this:
+"c1b9d5a2-f162-11cf-9ece-0020afc76f16".
+The
+.I UUID
+parameter may also be one of the following:
+.RS 1.2i
+.TP
+.I clear
+clear the filesystem UUID
+.TP
+.I random
+generate a new randomly-generated UUID
+.TP
+.I time
+generate a new time-based UUID
+.RE
.TP
.B \-v
Verbose execution.
Print the version number of
.B mke2fs
and exit.
+.TP
+.BI \-z " undo_file"
+Before overwriting a file system block, write the old contents of the block to
+an undo file. This undo file can be used with e2undo(8) to restore the old
+contents of the file system should something go wrong. If the empty string is
+passed as the undo_file argument, the undo file will be written to a file named
+mke2fs-\fIdevice\fR.e2undo in the directory specified via the
+\fIE2FSPROGS_UNDO_DIR\fR environment variable or the \fIundo_dir\fR directive
+in the configuration file.
+
+WARNING: The undo file cannot be used to recover from a power or system crash.
.SH ENVIRONMENT
.TP
.BI MKE2FS_SYNC
block group. This is mostly for debugging purposes.
.TP
.BI MKE2FS_DEVICE_SECTSIZE
+If set to non-zero integer value, its value is used to determine logical
+sector size of the
+.IR device .
+.TP
+.BI MKE2FS_DEVICE_PHYS_SECTSIZE
If set to non-zero integer value, its value is used to determine physical
sector size of the
.IR device .
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
.BR badblocks (8),
.BR dumpe2fs (8),
.BR e2fsck (8),
-.BR tune2fs (8)
+.BR tune2fs (8),
+.BR ext4 (5)
git://git.whamcloud.com / tools / e2fsprogs.git / blobdiff