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man_pages:linux:ubuntu:jammy:mke2fs_8

jammy (8) mkfs.ext3.8.gz

Provided by: e2fsprogs_1.46.5-2ubuntu1_amd64 bug

NAME

     mke2fs - create an ext2/ext3/ext4 file system

SYNOPSIS

     mke2fs  [ -c | -l filename ] [ -b block-size ] [ -C cluster-size ] [ -d root-directory ] [
     -D ] [ -g blocks-per-group ] [ -G number-of-groups ] [ -i bytes-per-inode ]  [  -I  inode-
     size  ] [ -j ] [ -J journal-options ] [ -N number-of-inodes ] [ -n ] [ -m reserved-blocks-
     percentage ] [ -o creator-os ] [ -O [^]feature[,...]  ] [ -q ] [ -r fs-revision-level ]  [
     -E extended-options ] [ -v ] [ -F ] [ -L volume-label ] [ -M last-mounted-directory ] [ -S
     ] [ -t fs-type ] [ -T usage-type ] [ -U UUID ]  [  -V  ]  [  -e  errors-behavior  ]  [  -z
     undo_file ] device [ fs-size ]
     mke2fs -O journal_dev [ -b block-size ] [ -L volume-label ] [ -n ] [ -q ] [ -v ] external-
     journal [ fs-size ]

DESCRIPTION

     mke2fs is used to create an ext2, ext3, or ext4 file system, usually in a  disk  partition
     (or file) named by device.
     The  file  system  size is specified by fs-size.  If fs-size does not have a suffix, it is
     interpreted as power-of-two kilobytes, unless the -b blocksize  option  is  specified,  in
     which  case  fs-size is interpreted as the number of 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 fs-size is omitted,
     mke2fs will create the file system based on the device size.
     If mke2fs is run as mkfs.XXX (i.e., mkfs.ext2, mkfs.ext3, or mkfs.ext4) the option -t  XXX
     is  implied;  so  mkfs.ext3  will  create  a file system for use with ext3, mkfs.ext4 will
     create a file system for use with ext4, and so on.
     The defaults of the parameters for the newly created file system, if not overridden by the
     options  listed below, are controlled by the /etc/mke2fs.conf configuration file.  See the
     mke2fs.conf(5) manual page for more details.

OPTIONS

  1. b block-size

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 -T option).  In most common cases, the
            default block size is 4k. If block-size is preceded by a negative sign ('-'),  then
            mke2fs  will  use  heuristics  to  determine  the  appropriate block size, with the
            constraint that the block size will be at least block-size bytes.  This  is  useful
            for certain hardware devices which require that the blocksize be a multiple of 2k.
  1. c 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.
  1. C cluster-size

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.  This  can  only
            be  specified  if  the bigalloc feature is enabled.  (See the ext4 (5) man page for
            more details about bigalloc.)   The default cluster size if bigalloc is enabled  is
            16 times the block size.
  1. d root-directory

Copy the contents of the given directory into the root directory of the file

            system.
  1. 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.
  1. e error-behavior

Change the behavior of the kernel code when errors are detected. In all cases, a

            file system error will cause e2fsck(8) to check the file system on the  next  boot.
            error-behavior can be one of the following:
                 continue    Continue normal execution.
                 remount-ro  Remount file system read-only.
                 panic       Cause a kernel panic.
  1. E extended-options

Set extended options for the file system. Extended options are comma separated,

            and may take an argument using the equals ('=') sign.  The -E option used to be  -R
            in  earlier  versions  of  mke2fs.   The  -R option is still accepted for backwards
            compatibility, but is deprecated.  The following extended options are supported:
                 encoding=encoding-name
                        Enable the casefold feature in the super block and set encoding-name as
                        the  encoding  to  be  used.   If  encoding-name  is not specified, the
                        encoding defined in mke2fs.conf(5) is used.
                 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.
                        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 strict which means that
                        invalid strings should be rejected by the file system.  In the  default
                        configuration, the strict flag is disabled.
                 mmp_update_interval=interval
                        Adjust the initial MMP update interval to interval seconds.  Specifying
                        an interval of 0 means to use  the  default  interval.   The  specified
                        interval  must be less than 300 seconds.  Requires that the mmp feature
                        be enabled.
                 stride=stride-size
                        Configure the file system for a RAID array with stride-size 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  chunk
                        size.   This  mostly  affects  placement  of  file system metadata like
                        bitmaps at mke2fs time to avoid placing them on a  single  disk,  which
                        can hurt performance.  It may also be used by the block allocator.
                 stripe_width=stripe-width
                        Configure  the  file  system  for  a  RAID array with stripe-width 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.
                 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.
                 resize=max-online-resize
                        Reserve enough space so that the block group descriptor table can  grow
                        to support a file system that has max-online-resize blocks.
                 lazy_itable_init[= <0 to disable, 1 to enable>]
                        If  enabled  and the uninit_bg feature is enabled, the inode table will
                        not be fully  initialized  by  mke2fs.   This  speeds  up  file  system
                        initialization  noticeably,  but  it  requires  the  kernel  to  finish
                        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.
                 lazy_journal_init[= <0 to disable, 1 to enable>]
                        If enabled, the journal inode will not be fully zeroed out  by  mke2fs.
                        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.
                 no_copy_xattrs
                        Normally mke2fs will copy the extended attributes of the files  in  the
                        directory  hierarchy specified via the (optional) -d option.  This will
                        disable the copy and leaves the files in the newly created file  system
                        without any extended attributes.
                 num_backup_sb=<0|1|2>
                        If  the  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.
                 packed_meta_blocks[= <0 to disable, 1 to enable>]
                        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.
                 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
                        mke2fs.   In  mke2fs  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  root_owner=  option  allows  explicitly
                        specifying these values, and avoid side-effects for users that  do  not
                        expect  the  contents  of  the  file system to change based on the user
                        running mke2fs.
                 test_fs
                        Set a flag in the file system superblock  indicating  that  it  may  be
                        mounted  using  experimental  kernel  code,  such  as  the ext4dev file
                        system.
                 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 file system initialization. This is set as default.
                 nodiscard
                        Do not attempt to discard blocks at mkfs time.
                 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 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.
  1. F Force mke2fs 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 mke2fs 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.
  1. 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 file system.
            (For  administrators who are creating file systems on RAID arrays, it is preferable
            to use the stride RAID parameter as part of the -E option rather than  manipulating
            the  number  of blocks per group.)  This option is generally used by developers who
            are developing test cases.
            If the bigalloc feature is enabled, the  -g  option  will  specify  the  number  of
            clusters in a block group.
  1. 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  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  flex_bg  file  system
            feature is enabled.
  1. i bytes-per-inode

Specify the bytes/inode ratio. mke2fs creates an inode for every bytes-per-inode

            bytes of space on the disk.  The larger the bytes-per-inode ratio, the fewer inodes
            will  be  created.  This value generally shouldn't 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 file system
            after it is created, so be careful deciding the correct value for  this  parameter.
            Note  that  resizing  a  file  system changes the number of inodes to maintain this
            ratio.
  1. I inode-size

Specify the size of each inode in bytes. The inode-size value must be a power of 2

            larger  or  equal to 128.  The larger the inode-size the more space the inode table
            will consume, and this reduces the usable 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.
            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.
            The  default  inode  size  is  controlled  by  the  mke2fs.conf(5)  file.   In  the
            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.
  1. j Create the file system with an ext3 journal. If the -J option is not specified,

the default journal parameters will be used to 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.
  1. J journal-options

Create the ext3 journal using options specified on the command-line. Journal

            options are comma separated, and may take an argument using the equals ('=')  sign.
            The following journal options are supported:
                 size=journal-size
                        Create an internal journal (i.e., stored inside  the  file  system)  of
                        size  journal-size megabytes.  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 file system blocks or
                        half the total file system size (whichever is smaller)
                 fast_commit_size=fast-commit-size
                        Create an additional fast commit journal area of size  fast-commit-size
                        kilobytes.  This option is only valid if fast_commit feature is enabled
                        on the file system. If this option is not specified and if  fast_commit
                        feature  is turned on, fast commit area size defaults to journal-size /
                        64 megabytes. The total size of the journal  with  fast_commit  feature
                        set  is  journal-size + ( 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).
                 location=journal-location
                        Specify the location of the journal.  The argument 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.
                 device=external-journal
                        Attach the file system to the journal block device located on external-
                        journal.  The external journal must already have been created using the
                        command
                        mke2fs -O journal_dev external-journal
                        Note that external-journal must have been created with the  same  block
                        size  as  the new file system.  In addition, while there is support for
                        attaching multiple file systems to a single external journal, the Linux
                        kernel  and e2fsck(8) do not currently support shared external journals
                        yet.
                        Instead of specifying a device name directly, external-journal can also
                        be  specified by either LABEL=label or UUID=UUID to locate the external
                        journal by  either  the  volume  label  or  UUID  stored  in  the  ext2
                        superblock  at  the start of the journal.  Use dumpe2fs(8) to display a
                        journal device's volume label and UUID.  See  also  the  -L  option  of
                        tune2fs(8).
            Only one of the size or device options can be given for a file system.
  1. l filename

Read the bad blocks list from 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  -c  option to mke2fs is a much simpler and less error-prone method of
            checking a disk for bad blocks before formatting it, as mke2fs  will  automatically
            pass the correct parameters to the badblocks program.
  1. L new-volume-label

Set the volume label for the file system to new-volume-label. The maximum length

            of the volume label is 16 bytes.
  1. m reserved-blocks-percentage

Specify the percentage of the file system blocks reserved for the super-user. This

            avoids  fragmentation,  and  allows  root-owned  daemons,  such  as  syslogd(8), to
            continue to function correctly after non-privileged processes  are  prevented  from
            writing to the file system.  The default percentage is 5%.
  1. M last-mounted-directory

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
            file system should be mounted.
  1. n Causes mke2fs 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 file system, so long as the mke2fs parameters
            that were passed when the file system was originally created are used again.  (With
            the -n option added, of course!)
  1. N number-of-inodes

Overrides the default calculation of the number of inodes that should be reserved

            for the file system (which is based on the number of blocks and the bytes-per-inode
            ratio).  This allows the user to specify the number of desired inodes directly.
  1. o creator-os

Overrides the default value of the “creator operating system” field of the file

            system.  The creator field is set by default to the  name  of  the  OS  the  mke2fs
            executable was compiled for.
  1. O [^]feature[,…]

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  base_features relation, either in the [defaults] section in the
            /etc/mke2fs.conf configuration file, or in the [fs_types] subsections for the usage
            types  as  specified  by  the  -T option, further modified by the features relation
            found in the [fs_types] subsections for the file system and usage types.   See  the
            mke2fs.conf(5)  manual  page  for  more  details.   The  file  system type-specific
            configuration setting found in the [fs_types]  section  will  override  the  global
            default found in [defaults].
            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  default_features
            relation  for  the  file system type being created, or in the [defaults] section of
            the configuration file.
            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 ('^') character.  Features with dependencies will not be  removed
            successfully.   The  pseudo-file  system  feature "none" will clear all file system
            features.
     For more information about the features which can be set, please see
            the manual page ext4(5).
  1. q Quiet execution. Useful if mke2fs is run in a script.
  1. r revision

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.
  1. S 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  by
            experienced users.  It causes mke2fs  to  reinitialize  the  superblock  and  group
            descriptors,  while  not  touching the inode table and the block and inode bitmaps.
            The e2fsck program should be run immediately after this option is used,  and  there
            is  no  guarantee  that  any  data will be salvageable.  Due to the wide variety of
            possible options to 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.
  1. t fs-type

Specify the file system type (i.e., ext2, ext3, ext4, etc.) that is to be created.

            If this option is not specified, 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 /etc/mke2fs.conf file.    This  option  controls
            which  file  system options are used by default, based on the fstypes configuration
            stanza in /etc/mke2fs.conf.
            If the -O 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 fs-type.  (e.g., "mke2fs -t ext3 -O extent /dev/sdXX"
            will create a file system that is not supported by the ext3 implementation as found
            in the Linux kernel; and "mke2fs -t ext3 -O ^has_journal /dev/hdXX" 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.)
  1. T usage-type[,…]

Specify how the file system is going to be used, so that mke2fs can choose optimal

            file  system  parameters  for  that  use.   The  usage types that are supported are
            defined in the configuration file /etc/mke2fs.conf.  The user may  specify  one  or
            more usage types using a comma separated list.
            If  this  option  is is not specified, mke2fs 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, mke2fs will use the file system type floppy.  If the file
            system size is greater than or equal to 3 but less than  512  megabytes,  mke2fs(8)
            will  use  the  file system type small.  If the file system size is greater than or
            equal to 4 terabytes but less than 16 terabytes, mke2fs(8) will use the file system
            type  big.   If  the  file  system  size  is greater than or equal to 16 terabytes,
            mke2fs(8) will use the file system type huge.  Otherwise, mke2fs(8)  will  use  the
            default file system type default.
  1. U UUID

Set the universally unique identifier (UUID) of the file system to UUID. The

            format of the UUID is a series of hex  digits  separated  by  hyphens,  like  this:
            "c1b9d5a2-f162-11cf-9ece-0020afc76f16".   The UUID parameter may also be one of the
            following:
                 clear  clear the file system UUID
                 random generate a new randomly-generated UUID
                 time   generate a new time-based UUID
  1. v Verbose execution.
  1. V Print the version number of mke2fs and exit.
  1. 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-
            device.e2undo in the directory specified  via  the  E2FSPROGS_UNDO_DIR  environment
            variable or the undo_dir directive in the configuration file.
            WARNING: The undo file cannot be used to recover from a power or system crash.

ENVIRONMENT

     MKE2FS_SYNC
            If  set to non-zero integer value, its value is used to determine how often sync(2)
            is called during inode table initialization.
     MKE2FS_CONFIG
            Determines the location of the configuration file (see mke2fs.conf(5)).
     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.
     MKE2FS_DEVICE_SECTSIZE
            If  set  to  non-zero  integer value, its value is used to determine logical sector
            size of the device.
     MKE2FS_DEVICE_PHYS_SECTSIZE
            If set to non-zero integer value, its value is used to  determine  physical  sector
            size of the device.
     MKE2FS_SKIP_CHECK_MSG
            If  set,  do  not  show  the message of file system automatic check caused by mount
            count or check interval.

AUTHOR

     This version of mke2fs has been written by Theodore Ts'o <[email protected]>.

AVAILABILITY

     mke2fs   is    part    of    the    e2fsprogs    package    and    is    available    from
     http://e2fsprogs.sourceforge.net.

SEE ALSO

     mke2fs.conf(5), badblocks(8), dumpe2fs(8), e2fsck(8), tune2fs(8), ext4(5)
man_pages/linux/ubuntu/jammy/mke2fs_8.txt · Last modified: 2023/08/15 16:40 by 127.0.0.1