.I block-size
]
[
+.B \-d
+.I root-directory
+]
+[
.B \-D
]
[
]
[
.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
-automagically figures the file system size. If called as
+will create the file system based on the device size.
+.PP
+If
+.B mke2fs
+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
.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. 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
+filesystem.
.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 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
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 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.
.TP
.BI 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 the
-@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.
+.TP
+.BI quotatype
+Specify which quota type ('usr' or 'grp') is to be
+initialized. This option has effect only if the
+.B quota
+feature is set. Without this extended option, the default
+behavior is to initialize both user and group quotas.
.RE
.TP
.BI \-f " fragment-size"
.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 ('^') or a minus ('-') character.
+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
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, is critical to specify exactly the same
+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 corretly, 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
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
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
git://git.whamcloud.com / tools / e2fsprogs.git / blobdiff