NAME | DESCRIPTION | THE [options] STANZA | THE [defaults] STANZA | THE [fs_types] STANZA | THE [devices] STANZA | FILES | SEE ALSO | COLOPHON

mke2fs.conf(5)               File Formats Manual              mke2fs.conf(5)

NAME         top

       mke2fs.conf - Configuration file for mke2fs

DESCRIPTION         top

       mke2fs.conf is the configuration file for mke2fs(8).  It controls the
       default parameters used by mke2fs(8) when it is creating ext2, ext3,
       or ext4 filesystems.

       The mke2fs.conf file uses an INI-style format.  Stanzas, or top-level
       sections, are delimited by square braces: [ ].  Within each section,
       each line defines a relation, which assigns tags to values, or to a
       subsection, which contains further relations or subsections.  An
       example of the INI-style format used by this configuration file
       follows below:

            [section1]
                 tag1 = value_a
                 tag1 = value_b
                 tag2 = value_c

            [section 2]
                 tag3 = {
                      subtag1 = subtag_value_a
                      subtag1 = subtag_value_b
                      subtag2 = subtag_value_c
                 }
                 tag1 = value_d
                 tag2 = value_e
            }

       Comments are delimited by a semicolon (';') or a hash ('#') character
       at the beginning of the comment, and are terminated by the end of
       line character.

       Tags and values must be quoted using double quotes if they contain
       spaces.  Within a quoted string, the standard backslash
       interpretations apply: "\n" (for the newline character), "\t" (for
       the tab character), "\b" (for the backspace character), and "\\" (for
       the backslash character).

       Some relations expect a boolean value.  The parser is quite liberal
       on recognizing ``yes'', '`y'', ``true'', ``t'', ``1'', ``on'', etc.
       as a boolean true value, and ``no'', ``n'', ``false'', ``nil'',
       ``0'', ``off'' as a boolean false value.

       The following stanzas are used in the mke2fs.conf file.  They will be
       described in more detail in future sections of this document.

       [options]
              Contains relations which influence how mke2fs behaves.

       [defaults]
              Contains relations which define the default parameters used by
              mke2fs(8).  In general, these defaults may be overridden by a
              definition in the fs_types stanza, or by an command-line
              option provided by the user.

       [fs_types]
              Contains relations which define defaults that should be used
              for specific file system and usage types.  The file system
              type and usage type can be specified explicitly using the
              -tand-T options to mke2fs(8), respectively.

THE [options] STANZA         top

       The following relations are defined in the [options] stanza.

       proceed_delay
              If this relation is set to a positive integer, then if mke2fs
              will proceed after waiting proceed_delay seconds, after asking
              the user for permission to proceed, even if the user has not
              answered the question.  Defaults to 0, which means to wait
              until the user answers the question one way or another.

THE [defaults] STANZA         top

       The following relations are defined in the [defaults] stanza.

       base_features
              This relation specifies the filesystems features which are
              enabled in newly created filesystems.  It may be overridden by
              the base_features relation found in the filesystem or usage
              type subsection of the [fs_types] stanza.

       default_features
              This relation specifies a set of features that should be added
              or removed to the features listed in the base_features
              relation.  It may be overridden by the filesystem-specific
              default_features in the filesystem or usage type subsection of
              [fs_types], and by the -O command-line option to mke2fs(8).

       enable_periodic_fsck
              This boolean relation specifies whether periodic filesystem
              checks should be enforced at boot time.  If set to true,
              checks will be forced every 180 days, or after a random number
              of mounts.  These values may be changed later via the -i and
              -c command-line options to tune2fs(8).

       force_undo
              This boolean relation, if set to a value of true, forces
              mke2fs to always try to create an undo file, even if the undo
              file might be huge and it might extend the time to create the
              filesystem image because the inode table isn't being
              initialized lazily.

       fs_type
              This relation specifies the default filesystem type if the
              user does not specify it via the -t option, or if mke2fs is
              not started using a program name of the form mkfs.fs-type.  If
              both the user and the mke2fs.conf file do not specify a
              default filesystem type, mke2fs will use a default filesystem
              type of ext3 if a journal was requested via a command-line
              option, or ext2 if not.

       undo_dir
              This relation specifies the directory where the undo file
              should be stored.  It can be overridden via the
              E2FSPROGS_UNDO_DIR environment variable.  If the directory
              location is set to the value none, mke2fs will not create an
              undo file.

       In addition, any tags that can be specified in a per-file system tags
       subsection as defined below (e.g., blocksize, hash_alg, inode_ratio,
       inode_size, reserved_ratio, etc.) can also be specified in the
       defaults stanza to specify the default value to be used if the user
       does not specify one on the command line, and the filesystem-type
       specific section of the configuration file does not specify a default
       value.

THE [fs_types] STANZA         top

       Each tag in the [fs_types] stanza names a filesystem type or usage
       type which can be specified via the -t or -T options to mke2fs(8),
       respectively.

       The mke2fs program constructs a list of fs_types by concatenating the
       filesystem type (i.e., ext2, ext3, etc.) with the usage type list.
       For most configuration options, mke2fs will look for a subsection in
       the [fs_types] stanza corresponding with each entry in the
       constructed list, with later entries overriding earlier filesystem or
       usage types.  For example, consider the following mke2fs.conf
       fragment:

       [defaults]
            base_features = sparse_super,filetype,resize_inode,dir_index
            blocksize = 4096
            inode_size = 256
            inode_ratio = 16384

       [fs_types]
            ext3 = {
                 features = has_journal
            }
            ext4 = {
                 features = extents,flex_bg
                 inode_size = 256
            }
            small = {
                 blocksize = 1024
                 inode_ratio = 4096
            }
            floppy = {
                 features = ^resize_inode
                 blocksize = 1024
                 inode_size = 128
            }

       If mke2fs started with a program name of mke2fs.ext4, then the
       filesystem type of ext4 will be used.  If the filesystem is smaller
       than 3 megabytes, and no usage type is specified, then mke2fs will
       use a default usage type of floppy.  This results in an fs_types list
       of "ext4, floppy".   Both the ext4 subsection and the floppy
       subsection define an inode_size relation, but since the later entries
       in the fs_types list supersede earlier ones, the configuration
       parameter for fs_types.floppy.inode_size will be used, so the
       filesystem  will have an inode size of 128.

       The exception to this resolution is the features tag, which specifies
       a set of changes to the features used by the filesystem, and which is
       cumulative.  So in the above example, first the configuration
       relation defaults.base_features would enable an initial feature set
       with the sparse_super, filetype, resize_inode, and dir_index features
       enabled.  Then configuration relation fs_types.ext4.features would
       enable the extents and flex_bg features, and finally the
       configuration relation fs_types.floppy.features would remove the
       resize_inode feature, resulting in a filesystem feature set
       consisting of the sparse_super, filetype, dir_index, extents_and
       flex_bg features.

       For each filesystem type, the following tags may be used in that
       fs_type's subsection.   These tags may also be used in the default
       section:

       base_features
              This relation specifies the features which are initially
              enabled for this filesystem type.  Only one base_features will
              be used, so if there are multiple entries in the fs_types list
              whose subsections define the base_features relation, only the
              last will be used by mke2fs(8).

       errors Change the behavior of the kernel code when errors are
              detected.  In all cases, a filesystem error will cause
              e2fsck(8) to check the filesystem on the next boot.  errors
              can be one of the following:

                   continue    Continue normal execution.

                   remount-ro  Remount filesystem read-only.

                   panic       Cause a kernel panic.

       features
              This relation specifies a comma-separated list of features
              edit requests which modify the feature set used by the newly
              constructed filesystem.  The syntax is the same as the -O
              command-line option to mke2fs(8); that is, a feature can be
              prefixed by a caret ('^') symbol to disable a named feature.
              Each feature relation specified in the fs_types list will be
              applied in the order found in the fs_types list.

       default_features
              This relation specifies set of features which should be
              enabled or disabled after applying the features listed in the
              base_features and features relations.  It may be overridden by
              the -O command-line option to mke2fs(8).

       auto_64-bit_support
              This relation is a boolean which specifies whether mke2fs(8)
              should automatically add the 64bit feature if the number of
              blocks for the file system requires this feature to be
              enabled.  The resize_inode feature is also automatically
              disabled since it doesn't support 64-bit block numbers.

       default_mntopts
              This relation specifies the set of mount options which should
              be enabled by default.  These may be changed at a later time
              with the -o command-line option to tune2fs(8).

       blocksize
              This relation specifies the default blocksize if the user does
              not specify a blocksize on the command line.

       lazy_itable_init
              This boolean relation specifies whether the inode table should
              be lazily initialized.  It only has meaning if the uninit_bg
              feature is enabled.  If lazy_itable_init is true and the
              uninit_bg feature is enabled,  the inode table will not be
              fully initialized by mke2fs(8).  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.

       journal_location
              This relation specifies the location of the journal.

       num_backup_sb
              This relation indicates whether file systems with the
              sparse_super2 feature enabled should be created with 0, 1, or
              2 backup superblocks.

       packed_meta_blocks
              This boolean relation specifes whether the allocation bitmaps,
              inode table, and journal should be located at the beginning of
              the file system.

       inode_ratio
              This relation specifies the default inode ratio if the user
              does not specify one on the command line.

       inode_size
              This relation specifies the default inode size if the user
              does not specify one on the command line.

       reserved_ratio
              This relation specifies the default percentage of filesystem
              blocks reserved for the super-user, if the user does not
              specify one on the command line.

       hash_alg
              This relation specifies the default hash algorithm used for
              the new filesystems with hashed b-tree directories.  Valid
              algorithms accepted are: legacy, half_md4, and tea.

       flex_bg_size
              This relation specifies 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.

       options
              This relation specifies additional extended options which
              should be treated by mke2fs(8) as if they were prepended to
              the argument of the -E option.  This can be used to configure
              the default extended options used by mke2fs(8) on a per-
              filesystem type basis.

       discard
              This boolean relation specifies whether the mke2fs(8) should
              attempt to discard device prior to filesystem creation.

       cluster_size
              This relation specifies the default cluster size if the
              bigalloc file system feature is enabled.  It can be overridden
              via the -C command line option to mke2fs(8)

       make_hugefiles
              This boolean relation enables the creation of pre-allocated
              files as part of formatting the file system.  The extent tree
              blocks for these pre-allocated files will be placed near the
              beginning of the file system, so that if all of the other
              metadata blocks are also configured to be placed near the
              beginning of the file system (by disabling the backup
              superblocks, using the packed_meta_blocks option, etc.), the
              data blocks of the pre-allocated files will be contiguous.

       hugefiles_uid
              This relation controls the user ownership for all of the files
              and directories created by the make_hugefiles feature.

       hugefiles_gid
              This relation controls the group ownership for all of the
              files and directories created by the make_hugefiles feature.

       hugefiles_umask
              This relation specifies the umask used when creating the files
              and directories by the make_hugefiles feature.

       num_hugefiles
              This relation specifies the number of huge files to be
              created.  If this relation is not specified, or is set to
              zero, and the hugefiles_size relation is non-zero, then
              make_hugefiles will create as many huge files as can fit to
              fill the entire file system.

       hugefiles_slack
              This relation specifies how much space should be reserved for
              other files.

       hugefiles_size
              This relation specifies the size of the huge files.  If this
              relation is not specified, the default is to fill the entire
              file system.

       hugefiles_align
              This relation specifies the alignment for the start block of
              the huge files.  It also forces the size of huge files to be a
              multiple of the requested alignment.  If this relation is not
              specified, no alignment requirement will be imposed on the
              huge files.

       hugefiles_align_disk
              This relations specifies whether the alignment should be
              relative to the beginning of the hard drive (assuming that the
              starting offset of the partition is available to mke2fs).  The
              default value is false, which will cause hugefile alignment to
              be relative to the beginning of the file system.

       hugefiles_name
              This relation specifies the base file name for the huge files.

       hugefiles_digits
              This relation specifies the (zero-padded) width of the field
              for the huge file number.

       zero_hugefiles
              This boolean relation specifies whether or not zero blocks
              will be written to the hugefiles while mke2fs(8) is creating
              them.  By default, zero blocks will be written to the huge
              files to avoid stale data from being made available to
              potentially untrusted user programs, unless the device
              supports a discard/trim operation which will take care of
              zeroing the device blocks.  By setting zero_hugefiles to
              false, this step will always be skipped, which can be useful
              if it is known that the disk has been previously erased, or if
              the user programs that will have access to the huge files are
              trusted to not reveal stale data.

THE [devices] STANZA         top

       Each tag in the [devices] stanza names device name so that per-device
       defaults can be specified.

       fs_type
              This relation specifies the default parameter for the -t
              option, if this option isn't specified on the command line.

       usage_types
              This relation specifies the default parameter for the -T
              option, if this option isn't specified on the command line.

FILES         top

       /etc/mke2fs.conf
              The configuration file for mke2fs(8).

SEE ALSO         top

       mke2fs(8)

COLOPHON         top

       This page is part of the e2fsprogs (utilities for ext2/3/4
       filesystems) project.  Information about the project can be found at
       ⟨http://e2fsprogs.sourceforge.net/⟩.  It is not known how to report
       bugs for this man page; if you know, please send a mail to
       man-pages@man7.org.  This page was obtained from the project's
       upstream Git repository 
       ⟨git://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git⟩ on 2017-07-05.
       If you discover any rendering problems in this HTML version of the
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       in this COLOPHON (which is not part of the original manual page),
       send a mail to man-pages@man7.org

E2fsprogs version 1.43.5-WIP    February 2017                 mke2fs.conf(5)

Pages that refer to this page: ext4(5)mke2fs(8)