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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 or ext3 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.

       [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
              filesystem types.  The filesystem type can be specified  explicitly  using  the  -T
              option to mke2fs(8).

THE [defaults] STANZA

       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 does 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.

       blocksize
              This relation specifies the default blocksize  if  the  user  does  not  specify  a
              blocksize  on  the  command  line,  and the filesystem-type specific section of the
              configuration file does not specify a blocksize.

       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.

       inode_ratio
              This relation specifies the default inode ratio 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 inode ratio.

       inode_size
              This relation specifies the default inode size 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 inode size.

       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, and the
              filesystem-type specific section of the  configuration  file  does  not  specify  a
              default reserved ratio. This value can be a floating point number.

       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.

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), 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 is 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, resize_inode, dir_index, extents_and flex_bg features.

       For each filesystem type, the following tags may be used in that fs_type's subsection:

       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).

       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 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.

       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)

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)