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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).

       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).

       force_undo
              This  relation, if set to a boolean 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.

       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).

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

       lazy_itable_init
              This  relation  is  a  boolean which 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.

       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 goups 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 goups
              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.

FILES

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

SEE ALSO

       mke2fs(8)