mke2fs.conf(5)



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

NAME
       mke2fs.conf - Configuration file for mke2fs

DESCRIPTION
       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  exam-
       ple  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 spa-
       ces.   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 charac-
       ter).

       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 a  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.

       [devices]
              Contains relations which define defaults for specific devices.

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

       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 sec-
       tion of the configuration file does not specify a default value.

THE [fs_types] STANZA
       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), respec-
       tively.

       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 filesys-
       tem 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, result-
       ing  in  a filesystem feature set consisting of the sparse_super, file-
       type, 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 sec-
       tion:

       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 sub-
              sections  define  the base_features relation, only the last will
              be used by 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).

       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  fol-
              lowing:

                   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  con-
              structed  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.

       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.

       default_features
              This  relation specifies set of features which should be enabled
              or disabled after applying the features listed in the  base_fea-
              tures  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 initializa-
              tion noticeably, but it requires the kernel to finish initializ-
              ing  the  filesystem  in  the  background when the filesystem is
              first mounted.

       lazy_journal_init
              This boolean relation specifies whether the journal inode should
              be  lazily  initialized.  It only has meaning if the has_journal
              feature is enabled. If lazy_journal_init is  true,  the  journal
              inode  will  not  be fully zeroed out by mke2fs.  This speeds up
              filesystem initialization noticeably,  but  carries  some  small
              risk if the system crashes before the journal has been overwrit-
              ten entirely one time.

       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 specifies 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 algo-
              rithms 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  perfor-
              mance  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  argu-
              ment  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 meta-
              data 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_dir
              This  relation specifies the directory where huge files are cre-
              ated, relative to the filesystem root.

       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 mul-
              tiple of the requested alignment.  If this relation is not spec-
              ified,  no  alignment  requirement  will  be imposed on the huge
              files.

       hugefiles_align_disk
              This relations specifies whether the alignment should  be  rela-
              tive  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 dis-
              card/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
       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
       /etc/mke2fs.conf
              The configuration file for mke2fs(8).

SEE ALSO
       mke2fs(8)

E2fsprogs version 1.43.9         February 2018                  mke2fs.conf(5)

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