.\"
.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 \-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
@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
.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. This mostly affects placement of filesystem
+metadata like bitmaps at
+.BR mke2fs (2)
+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 disks in the RAID (e.g. RAID 5 N+1, RAID 6 N+2).
+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 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 \-R
+option rather than manipulating the number of blocks per group.)
+This option is generally used by developers who
+are developing test cases.
.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
+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.
-The journal must fit within the newly created filesystem.
@JDEV@.TP
@JDEV@.BI device= external-journal
@JDEV@Attach the filesystem to the journal block device located on
@JDEV@The external
@JDEV@journal must already have been created using the command
@JDEV@.IP
-@JDEV@.B mke2fs -O journal_dev
-@JDEV@.IR external-journal
+@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
.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%.
+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
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. Filesystems that
-may need to mounted on pre-2.2 kernels should be created with
-.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.
+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 filesystem type as specified by the
+.B -T
+option. The filesystem type-specific configuration setting found in
+the
+.I [fs_types]
+section will override the global default found in
+.IR [libdefaults] .
.sp
-The following filesystem options are supported:
+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 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.
@JDEV@.I external-journal
@JDEV@must be created with the same
@JDEV@block size as the filesystems that will be using it.
+.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
+.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
kernels only support revision 0 filesystems. The default is to
create revision 1 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. The
-following options are supported:
-.RS 1.2i
-.TP
-.BI stride= stripe-size
-Configure the filesystem for a RAID array with
-.I stripe-size
-filesystem blocks per stripe.
-.RE
-.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
.\" 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
-.TP
-largefile4
-one inode per 4 megabytes
-.RE
+Specify how the filesystem is going to be used, so that
+.B mke2fs
+can choose optimal filesystem parameters for that use. The filesystem
+types that are can be supported are defined in the configuration file
+.BR /etc/mke2fs.conf (5).
+The default configuration file contains definitions for the filesystem
+types: small, floppy, news, largefile, and largefile4.
.TP
.B \-v
Verbose execution.
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