.\" -*- nroff -*-
.\" Copyright 1993, 1994, 1995 by Theodore Ts'o. All Rights Reserved.
.\" This file may be copied under the terms of the GNU Public License.
-.\"
+.\"
.TH MKE2FS 8 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
.SH NAME
mke2fs \- create an ext2/ext3 filesystem
.B mke2fs
[
.B \-c
-|
+|
.B \-l
.I filename
]
.I blocks-per-group
]
[
+.B \-G
+.I number-of-groups
+]
+[
.B \-i
.I bytes-per-inode
]
.I number-of-inodes
]
[
-.B -n
+.B \-n
]
[
.B \-m
.I creator-os
]
[
-.B \-O
+.B \-O
.IR feature [,...]
]
[
.B \-S
]
[
+.B \-t
+.I fs-type
+]
+[
.B \-T
-.I filesystem-type
+.I usage-type
+]
+[
+.B \-U
+.I UUID
]
[
.B \-V
.B mke2fs
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
+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,
.SH OPTIONS
.TP
.BI \-b " block-size"
-Specify the size of blocks in bytes. Valid block size vales are 1024,
+Specify the size of blocks in bytes. Valid block-size values are 1024,
2048 and 4096 bytes per block. If omitted,
-.B mke2fs
-block-size is heuristically determined by the file system size and
+block-size is heuristically determined by the filesystem size and
the expected usage of the filesystem (see the
.B \-T
-option). If
+option). If
.I block-size
-is negative, then
+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
+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. If
-this option is specified twice, then a slower, read-write
+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
+.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
+The
+.B \-R
+option is still accepted for backwards compatibility. The
following extended options are supported:
.RS 1.2i
.TP
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.
+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
+.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
.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).
+filesystem 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 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.
+to support a filesystem that has
+.I 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 be fully initialized by
+.BR mke2fs .
+This speeds up filesystem
+initialization noticeably, 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
Specify the size of fragments in bytes.
.TP
.B \-F
-Force
+Force
.B mke2fs
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
+In order to force
.B mke2fs
-to create a filesystem even if the filesystem appears to be in use
+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
+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
.I stride
RAID parameter as part of the
-.B \-R
-option rather than manipulating the number of blocks per group.)
+.B \-E
+option rather than manipulating the number of blocks per group.)
This option is generally used by developers who
-are developing test cases.
+are developing test cases.
+.TP
+.BI \-G " number-of-groups"
+Specify the number of block groups 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 groups 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.
+Specify the bytes/inode ratio.
.B mke2fs
creates an inode for every
.I bytes-per-inode
-bytes of space on the disk. The larger the
+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 then too many
-inodes will be made. Be warned that is not possible to expand the number
+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.
+correct value for this parameter.
.TP
.BI \-I " inode-size"
-Specify the size of each inode in bytes.
+Specify the size of each inode in bytes.
.B mke2fs
-creates 128-byte inodes by default. In kernels after 2.6.10 and some
-earlier vendor kernels it is possible to utilize larger inodes to store
-extended attributes for improved performance. The
+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
+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. Using
-the default value is always safe, though it may be desirable to use 256-byte
-inodes if full backward compatibility is not a concern. Extended attributes
+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
+.TP
.B \-j
Create the filesystem 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)
+create an appropriately sized journal (given the size of the filesystem)
stored within the filesystem. Note that you must be using a kernel
which has ext3 support in order to actually make use of the journal.
.TP
.TP
.BI size= journal-size
Create an internal journal (i.e., stored inside the filesystem) of size
-.I journal-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 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.
@JDEV@.TP
@JDEV@.BI device= external-journal
@JDEV@Attach the filesystem to the journal block device located on
@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@the Linux kernel and
@JDEV@.BR e2fsck (8)
@JDEV@do not currently support shared external journals yet.
@JDEV@.IP
.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
+using the same block size as used by
+.BR mke2fs .
+As a result, the
.B \-c
-option to
+option to
.B mke2fs
is a much simpler and less error-prone method of checking a disk for bad
-blocks before formatting it, as
+blocks before formatting it, as
.B mke2fs
will automatically pass the correct parameters to the
.B badblocks
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 filesystem blocks reserved for
the super-user. This avoids fragmentation, and allows root-owned
-daemons, such as
+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
+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
+.BI \-M " last-mounted-directory"
+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 filesystem should be mounted.
.TP
.B \-n
-causes mke2fs to not actually create a filesystem, but display what it
+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
determine the location of the backup superblocks for a particular
-filesystem, so long as the mke2fs parameters that were passed when the
+filesystem, so long as the
+.B mke2fs
+parameters that were passed when the
filesystem was originally created are used again. (With the
-.B \-n
+.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
-the
+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
+the
.I bytes-per-inode
-ratio). This allows the user to specify the number
+ratio). This allows the user to specify the number
of desired inodes directly.
.TP
.BI \-o " creator-os"
-Manually override the default value of the "creator os" field of the
-filesystem. Normally the creator field is set by default to the native OS
-of the
+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
.B mke2fs
-executable.
+executable was compiled for.
.TP
.B "\-O \fIfeature\fR[,...]"
-Create filesystem with given features (filesystem options), overriding
-the default filesystem options. The default features which are
+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
.I base_features
relation, either in the
-.I [libdefaults]
+.I [defaults]
section in the
.B /etc/mke2fs.conf
-configuration file, or in the subsection of the
+configuration file,
+or in the
+.I [fs_types]
+subsections 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 for the filesystem type as specified by the
-.B -T
-option. The filesystem type-specific configuration setting found in
-the
+subsections for 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] .
+.IR [defaults] .
.sp
-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
+The filesystem 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
-.I [libdefaults]
+relation for the filesystem 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
by commas, that are to be enabled. To disable a feature, simply
-prefix the feature name with a caret ('^') character. The
+prefix the feature name with a caret ('^') character. The
pseudo-filesystem feature "none" will clear all filesystem features.
.RS 1.2i
.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
@JDEV@must be created with the same
@JDEV@block size as the filesystems that will be using it.
.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 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.
+.TP
.B resize_inode
Reserve space so the block group descriptor table may grow in the future.
-Useful for online resizing using
+Useful for online resizing using
.BR resize2fs .
-By default
+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
+using the
.B resize
extended option.
.TP
.RE
.TP
.B \-q
-Quiet execution. Useful if
+Quiet execution. Useful if
.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
+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
-recovery method is desired. It causes
+recovery method is desired. It causes
.B mke2fs
-to reinitialize the
+to reinitialize the
superblock and group descriptors, while not touching the inode table
and the block and inode bitmaps. The
.B e2fsck
.\" 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
-.B mke2fs
-can choose optimal filesystem parameters for that use. The filesystem
-types that are can be supported are defined in the configuration file
+.BI \-t " fs-type"
+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)
+file. This option controls which filesystem options are used by
+default, based on the
+.B fstypes
+configuration stanza in
+.BR /etc/mke2fs.conf (5).
+.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
+.IR fs-type .
+(e.g., "\fBmke2fs -t ext3 -O extents /dev/sdXX\fR" will create a
+filesystem 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.)
+.TP
+.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 default configuration file contains definitions for the filesystem
-types: small, floppy, news, largefile, and largefile4.
+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
+.BI \-U " UUID"
+Create the filesystem with the specified UUID.
.TP
.B \-v
Verbose execution.
.TP
.B \-V
-Print the version number of
+Print the version number of
.B mke2fs
and exit.
.SH AUTHOR
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
+is part of the e2fsprogs package and is available from
http://e2fsprogs.sourceforge.net.
.SH SEE ALSO
.BR mke2fs.conf (5),
git://git.whamcloud.com / tools / e2fsprogs.git / blobdiff