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mke2fs.conf(5)									   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 delim-
       ited  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  subsec-
       tions.  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 charac-
       ter), "\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  gen-
	      eral,  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  filesys-
	      tem  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 block-
	      size  on the command line, and the filesystem-type specific section of the configu-
	      ration 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 spec-
       ified 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  speci-
       fied,  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 fea-
       tures, 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  filesys-
	      tem 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 mod-
	      ify 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  speci-
	      fied 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 block-
	      size 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.

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

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

SEE ALSO
       mke2fs(8)

E2fsprogs version 1.41.14		  December 2010 			   mke2fs.conf(5)
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