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 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 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 spaces.  Within a quoted string, the standard backslash interpretations
       apply: "
" (for the newline character), "	" (for the tab character), "" (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 defini-
	      tion 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 spe-
	      cific 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  spe-
	      cific 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 envi-
	      ronment 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  con-
	      figure 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)

E2fsprogs version 1.41.11					    March 2010							    mke2fs.conf(5)