.\"
.TH MKE2FS 8 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
.SH NAME
-mke2fs \- create an ext2/ext3/ext4 filesystem
+mke2fs \- create an ext2/ext3/ext4 file system
.SH SYNOPSIS
.B mke2fs
[
.I block-size
]
[
-.B \-D
+.B \-C
+.I cluster-size
+]
+[
+.B \-d
+.I root-directory
]
[
-.B \-f
-.I fragment-size
+.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,
+is used to create an ext2, ext3, or ext4 file system, usually in a disk
+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
+The defaults of the parameters for the newly created file system, if not
overridden by the options listed below, are controlled by the
.B /etc/mke2fs.conf
configuration file. See the
.SH OPTIONS
.TP
.BI \-b " block-size"
-Specify the size of blocks in bytes. Valid block-size values are 1024,
-2048 and 4096 bytes per block. If omitted,
-block-size is heuristically determined by the filesystem size and
-the expected usage of the filesystem (see the
+Specify the size of blocks in bytes. Valid block-size values are powers of two
+from 1024 up to 65536 (however note that the kernel is able to mount only
+file systems with block-size smaller or equal to the system page size - 4k on
+x86 systems, up to 64k on ppc64 or aarch64 depending on kernel configuration).
+If omitted, block-size is heuristically determined by the file system size and
+the expected usage of the file system (see the
.B \-T
-option). If
+option). In most common cases, the default block size is 4k. If
.I block-size
is preceded by a negative sign ('-'), then
.B mke2fs
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
+Specify the size of cluster in bytes for file systems using the bigalloc
feature. Valid cluster-size values are from 2048 to 256M bytes per
-cluster. By default (if bigalloc is enabled and no cluster size is
-otherwise specified using this option), the cluster size will be 16
-times the block size.
+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
+file system.
.TP
.B \-D
Use direct I/O when writing to the disk. This avoids mke2fs dirtying a
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 file system error will cause
+.BR e2fsck (8)
+to check the file system 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 file system 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
+Set extended options for the file system. Extended options are comma
separated, and may take an argument using the equals ('=') sign. The
.B \-E
option used to be
The following extended options are supported:
.RS 1.2i
.TP
+.BI encoding= encoding-name
+Enable the
+.I casefold
+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 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
feature be enabled.
.TP
.BI stride= stride-size
-Configure the filesystem for a RAID array with
+Configure the file system for a RAID array with
.I stride-size
-filesystem blocks. This is the number of blocks read or written to disk
+file system 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
+This mostly affects placement of file system 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
+Configure the file system for a RAID array with
.I stripe-width
-filesystem blocks per stripe. This is typically stride-size * N, where
+file system 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 offset= offset
+Create the file system 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
+to support a file system that has
.I max-online-resize
blocks.
.TP
If enabled and the uninit_bg feature is enabled, the inode table will
not be fully initialized by
.BR mke2fs .
-This speeds up filesystem
+This speeds up file system
initialization noticeably, but it requires the kernel to finish
-initializing the filesystem in the background when the filesystem is
+initializing the file system in the background when the file system is
first mounted. If the option value is omitted, it defaults to 1 to
enable lazy inode table zeroing.
.TP
.B lazy_journal_init\fR[\fB= \fI<0 to disable, 1 to enable>\fR]
If enabled, the journal inode will not be fully zeroed out by
.BR mke2fs .
-This speeds up filesystem initialization noticeably, but carries some
+This speeds up file system initialization noticeably, but carries some
small risk if the system crashes before the journal has been overwritten
entirely one time. If the option value is omitted, it defaults to 1 to
enable lazy journal inode zeroing.
.TP
+.B 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.
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.
+file system 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.
+Set a flag in the file system superblock indicating that it may be
+mounted using experimental kernel code, such as the ext4dev file system.
.TP
-.BI discard
+.B discard
Attempt to discard blocks at mkfs time (discarding blocks initially is useful
on solid state devices and sparse / thin-provisioned storage). When the device
advertises that discard also zeroes data (any subsequent read after the discard
and before write returns zero), then mark all not-yet-zeroed inode tables as
-zeroed. This significantly speeds up filesystem initialization. This is set
+zeroed. This significantly speeds up file system initialization. This is set
as default.
.TP
-.BI nodiscard
+.B nodiscard
Do not attempt to discard blocks at mkfs time.
-@QUOTA_MAN_COMMENT@.TP
-@QUOTA_MAN_COMMENT@.BI quotatype
-@QUOTA_MAN_COMMENT@Specify which quota type ('usr' or 'grp') is to be
-@QUOTA_MAN_COMMENT@initialized. This option has effect only if
-@QUOTA_MAN_COMMENT@.B quota
-@QUOTA_MAN_COMMENT@feature is set. Without this extended option, the default
-@QUOTA_MAN_COMMENT@behavior is to initialize both user and group quotas.
-.RE
.TP
-.BI \-f " fragment-size"
-Specify the size of fragments in bytes.
+.B 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
.B mke2fs
-to create a filesystem, even if the specified device is not a partition
+to create a file system, 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
+to create a file system even if the file system 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
+for the file system. (For administrators who are creating
+file systems on RAID arrays, it is preferable to use the
.I stride
RAID parameter as part of the
.B \-E
.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
+ext4 file system. 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.
+file system feature is enabled.
.TP
.BI \-i " bytes-per-inode"
Specify the bytes/inode ratio.
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 in that case more
+be smaller than the blocksize of the file system, since in that case more
inodes would be made than can ever be used. Be warned that it is not
-possible to change this ratio on a filesystem after it is created, so be
+possible to change this ratio on a file system after it is created, so be
careful deciding the correct value for this parameter. Note that resizing
-a filesystem changes the numer of inodes to maintain this ratio.
+a file system 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.
-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.
+space in the file system and can also negatively impact performance.
+It is not
+possible to change this value after the file system is created.
+.IP
+File systems with an inode size of 128 bytes do not support timestamps
+beyond January 19, 2038. Inodes which are 256 bytes or larger will
+support extended timestamps, project id's, and the ability to store some
+extended attributes in the inode table for improved performance.
+.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
+Create the file system 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
+create an appropriately sized journal (given the size of the file system)
+stored within the file system. 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"
.RS 1.2i
.TP
.BI size= journal-size
-Create an internal journal (i.e., stored inside the filesystem) of size
+Create an internal journal (i.e., stored inside the file system) of size
.I journal-size
megabytes.
-The size of the journal must be at least 1024 filesystem blocks
+The size of the journal must be at least 1024 file system blocks
(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
+and may be no more than 10,240,000 file system blocks or half the total
file system size (whichever is smaller)
+.TP
+.BI fast_commit_size= fast-commit-size
+Create an additional fast commit journal area of size
+.I fast-commit-size
+kilobytes.
+This option is only valid if
+.B fast_commit
+feature is enabled
+on the file system. If this option is not specified and if
+.B fast_commit
+feature is turned on, fast commit area size defaults to
+.I journal-size
+/ 64 megabytes. The total size of the journal with
+.B fast_commit
+feature set is
+.I journal-size
++ (
+.I fast-commit-size
+* 1024) megabytes. The total journal size may be no more than
+10,240,000 file system 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
+@JDEV@Attach the file system 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@Note that
@JDEV@.I external-journal
@JDEV@must have been created with the
-@JDEV@same block size as the new filesystem.
+@JDEV@same block size as the new file system.
@JDEV@In addition, while there is support for attaching
-@JDEV@multiple filesystems to a single external journal,
+@JDEV@multiple file systems 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@Only one of the
@JDEV@.BR size " or " device
-@JDEV@options can be given for a filesystem.
+@JDEV@options can be given for a file system.
.TP
.BI \-l " filename"
Read the bad blocks list from
program.
.TP
.BI \-L " new-volume-label"
-Set the volume label for the filesystem to
+Set the volume label for the file system 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
+Specify the percentage of the file system 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
+prevented from writing to the file system. The default percentage
is 5%.
.TP
.BI \-M " last-mounted-directory"
-Set the last mounted directory for the filesystem. This might be useful
+Set the last mounted directory for the file system. 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.
+determine where the file system should be mounted.
.TP
.B \-n
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
+to not actually create a file system, but display what it
+would do if it were to create a file system. This can be used to
determine the location of the backup superblocks for a particular
-filesystem, so long as the
+file system, so long as the
.B mke2fs
parameters that were passed when the
-filesystem was originally created are used again. (With the
+file system 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
+reserved for the file system (which is based on the number of blocks and
the
.I bytes-per-inode
ratio). This allows the user to specify the number
.TP
.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
+file system. The creator field is set by default to the name of the OS the
.B mke2fs
executable was compiled for.
.TP
-.B "\-O \fIfeature\fR[,...]"
-Create a filesystem with the given features (filesystem options),
-overriding the default filesystem options. The features that are
+.B "\-O \fR[^]\fIfeature\fR[,...]"
+Create a file system with the given features (file system options),
+overriding the default file system options. The features that are
enabled by default are specified by the
.I base_features
relation, either in the
.I features
relation found in the
.I [fs_types]
-subsections for the filesystem and usage types. See the
+subsections for the file system and usage types. See the
.BR mke2fs.conf (5)
manual page for more details.
-The filesystem type-specific configuration setting found in the
+The file system 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
+The file system 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
+relation for the file system 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
+The file system 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 ('^') or a minus ('-') character.
-Features with dependents will not be removed successfully.
-The pseudo-filesystem feature "none" will clear all filesystem features.
-.RS 1.2i
-.TP
-.B 64bit
-.br
-Enables the file system to be larger than 2^32 blocks. This feature is set
-automatically, as needed, but it can be useful to specify this feature
-explicitly if the file system might need to be resized larger than 2^32
-blocks, even if it was smaller than that threshold when it was
-originally created. Note that some older kernels and older versions
-of e2fsprogs will not support file systems with this feature enabled.
-.TP
-.B bigalloc
-.br
-This feature enables clustered block allocation, so that the unit of
-allocation is a power of two number of blocks. That is, each bit in the
-what had traditionally been known as the block allocation bitmap now
-indicates whether a cluster is in use or not, where a cluster is by
-default composed of 16 blocks. This feature can decrease the time
-spent on doing block allocation and brings smaller fragmentation, especially
-for large files. The size can be specified using the
-.B \-C option.
-.IP
-.B Warning:
-The bigalloc feature is still under development, and may not be fully
-supported with your kernel or may have various bugs. Please see the web
-page http://ext4.wiki.kernel.org/index.php/Bigalloc for details.
-May clash with delayed allocation (see
-.BR nodelalloc mount option).
-.IP
-This feature requires that the
-.B extent
-features be enabled.
-.TP
-.B dir_index
-.br
-Use hashed b-trees to speed up name lookups in large directories.
-.TP
-.B dir_nlink
-.br
-Allow more than 65000 subdirectories per directory.
-.TP
-.B extent
-.br
-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. (Note: both
-.B extent
-and
-.B extents
-are accepted as valid names for this feature for
-historical/backwards compatibility reasons.)
-.TP
-.B extra_isize
-.br
-This feature reserves a specific amount of space in each inode for
-extended metadata such as nanosecond timestamps and file creation time,
-even if the current kernel does not current need to reserve this much
-space. Without this feature, the kernel will reserve the amount of
-space for features currently it currently needs, and the rest may be
-consumed by extended attributes.
-
-For this feature to be useful the inode size must be 256 bytes in size
-or larger.
+prefix the feature name with a caret ('^') character.
+Features with dependencies will not be removed successfully.
+The pseudo-file system feature "none" will clear all file system features.
.TP
-.B ext_attr
-.br
-This feature enables the use of extended attributes.
-.TP
-.B filetype
-.br
-This feature enables the storage file type information in directory
-entries. It is normally enabled by default for all file system types.
-.TP
-.B flex_bg
-.br
-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
-.br
-Create a journal to ensure filesystem consistency even across unclean
-shutdowns. Setting the filesystem feature is equivalent to using the
-.B \-j
-option.
-.TP
-.B huge_file
-.br
-Allows files larger than 2TiB in size.
-.TP
-.B journal_dev
-.br
-Creates an external ext3 journal on the given device
-instead of a regular ext2 filesystem.
-Note that
-.I external-journal
-must be created with the same
-block size as the filesystems that will be using it.
-.IP
-Once ready, use
-.BR mke2fs (8)
-or
-.BR tune2fs(8)
-with
-.B \-J
-.BR device= <external-device>
-to direct a filesystem to the journaling device (see journal-options).
-.TP
-.B large_file
-.br
-Filesystem can contain files that are greater than 2GiB. (Modern kernels
-set this feature automatically when a file > 2GiB is created.)
-.\" .TP
-.\" .B metadata_csum
-.\" .br
-.\" Filesystem supports metadata checksumming. This feature stores
-.\" checksums for all of the filesystem metadata (superblock, group
-.\" descriptor blocks, inode and block bitmaps, directories, and
-.\" extent tree blocks). The checksum algorithm used for the metadata
-.\" blocks is different than the one used for group descriptors with the
-.\" .B uninit_bg
-.\" feature, these two features are incompatible and
-.\" .B metadata_csum
-.\" will be used preferentially instead of
-.\" .BR uninit_bg .
-.\" .br
-.\" .B Future feature, available in e2fsprogs 1.43-WIP
-.TP
-.B meta_bg
-.br
-This feature allows file systems to be resized on-line without explicitly
-needing to reserve space for growth in the size of the block group
-descriptors. This scheme is also used to resize file systems which are
-larger than 2^32 blocks. It is not recommended that this feature be set
-when a file system is created, since this alternate method of storing
-the block group descriptor will slow down the time needed to mount the
-file system, and newer kernels can automatically set this feature as
-necessary when doing an online resize and no more reserved space is
-available in the resize inode.
-.TP
-.B mmp
-.br
-Multiple mount protection (MMP) feature. MMP helps to
-protect the filesystem from being multiply mounted and is useful in
-shared storage environments.
-@QUOTA_MAN_COMMENT@.TP
-@QUOTA_MAN_COMMENT@.B quota
-@QUOTA_MAN_COMMENT@.br
-@QUOTA_MAN_COMMENT@Create quota inodes (inode #3 for userquota and inode
-@QUOTA_MAN_COMMENT@#4 for group quota) and set them in the superblock.
-@QUOTA_MAN_COMMENT@With this feature, the quotas will be enabled
-@QUOTA_MAN_COMMENT@automatically when the filesystem is mounted.
-@QUOTA_MAN_COMMENT@.IP
-@QUOTA_MAN_COMMENT@Causes the quota files (i.e., user.quota and
-@QUOTA_MAN_COMMENT@group.quota which existed
-@QUOTA_MAN_COMMENT@in the older quota design) to be hidden inodes.
-@QUOTA_MAN_COMMENT@.IP
-@QUOTA_MAN_COMMENT@.B Not defined by default,
-@QUOTA_MAN_COMMENT@see https://ext4.wiki.kernel.org/index.php/Quota
-.TP
-.B resize_inode
-.br
-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.
-.IP
- This feature requires that the
-.B sparse_super
-feature be enabled.
-.TP
-.B sparse_super
-.br
-Create a filesystem with fewer superblock backup copies
-(saves space on large filesystems). This feature is normally enabled by
-default for all file systems.
-.TP
-.B uninit_bg
-.br
-Create a filesystem without initializing all of the block groups. This
-feature allows the kernel to initialize bitmaps and inode tables
-and keep a high watermark for the unused inodes in a filesystem, to reduce
-.BR e2fsck (8)
-time. The result is that it can speed up filesystem creation time noticeably
-(if lazy_itable_init is enabled).
-.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
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.
+Set the file system revision for the new file system. Note that 1.2
+kernels only support revision 0 file systems. The default is to
+create revision 1 file systems.
.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
+.B 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 file system will be further
+corrupted. In some cases, such as file systems 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 file system
+corruption will occur. It is best to run this on a full copy of the
+file system 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
+Specify the file system type (i.e., ext2, ext3, ext4, etc.) that is
to be created.
If this option is not specified,
.B mke2fs
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
.B /etc/mke2fs.conf
-file. This option controls which filesystem options are used by
+file. This option controls which file system options are used by
default, based on the
.B fstypes
configuration stanza in
.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
+option is used to explicitly add or remove file system options that
+should be set in the newly created file system, the
+resulting file system may not be supported by the requested
.IR fs-type .
(e.g., "\fBmke2fs \-t ext3 \-O extent /dev/sdXX\fR" will create a
-filesystem that is not supported by the ext3 implementation as found in
+file system 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.)
+will create a file system that does not have a journal and hence will not
+be supported by the ext3 file system code in the Linux kernel.)
.TP
.BI \-T " usage-type[,...]"
-Specify how the filesystem is going to be used, so that
+Specify how the file system is going to be used, so that
.B mke2fs
-can choose optimal filesystem parameters for that use. The usage
+can choose optimal file system parameters for that use. The usage
types that are supported are defined in the configuration file
.BR /etc/mke2fs.conf .
The user may specify one or more usage types
.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,
+will pick a single default usage type based on the size of the file system to
+be created. If the file system size is less than 3 megabytes,
.B mke2fs
-will use the filesystem type
+will use the file system type
.IR floppy .
-If the filesystem size is greater than 3 but less than or equal to
+If the file system size is greater than or equal to 3 but less than
512 megabytes,
.BR mke2fs (8)
-will use the filesystem type
+will use the file system type
.IR small .
-If the filesystem size is greater than or equal to 4 terabytes but less than
+If the file system size is greater than or equal to 4 terabytes but less than
16 terabytes,
.BR mke2fs (8)
-will use the filesystem type
+will use the file system type
.IR big .
-If the filesystem size is greater than or equal to 16 terabytes,
+If the file system size is greater than or equal to 16 terabytes,
.BR mke2fs (8)
-will use the filesystem type
+will use the file system type
.IR huge .
Otherwise,
.BR mke2fs (8)
-will use the default filesystem type
+will use the default file system type
.IR default .
.TP
.BI \-U " UUID"
-Create the filesystem with the specified UUID.
+Set the universally unique identifier (UUID) of the file system 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 file system 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
+.B MKE2FS_SYNC
If set to non-zero integer value, its value is used to determine how often
.BR sync (2)
is called during inode table initialization.
.TP
-.BI MKE2FS_CONFIG
+.B MKE2FS_CONFIG
Determines the location of the configuration file (see
.BR mke2fs.conf (5)).
.TP
-.BI MKE2FS_FIRST_META_BG
+.B MKE2FS_FIRST_META_BG
If set to non-zero integer value, its value is used to determine first meta
block group. This is mostly for debugging purposes.
.TP
-.BI MKE2FS_DEVICE_SECTSIZE
+.B MKE2FS_DEVICE_SECTSIZE
+If set to non-zero integer value, its value is used to determine logical
+sector size of the
+.IR device .
+.TP
+.B MKE2FS_DEVICE_PHYS_SECTSIZE
If set to non-zero integer value, its value is used to determine physical
sector size of the
.IR device .
.TP
-.BI MKE2FS_SKIP_CHECK_MSG
-If set, do not show the message of filesystem automatic check caused by
+.B MKE2FS_SKIP_CHECK_MSG
+If set, do not show the message of file system automatic check caused by
mount count or check interval.
.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
.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