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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 be-
       low:

	    [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.

       [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 en-
	      abled 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	 algo-
	      rithms 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 sec-
	      tion of the configuration	file does not specify  a  default  re-
	      served 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  en-
	      vironment	 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), 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 de-
       fault 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	speci-
       fies a set of changes to	the features used by the filesystem, and which
       is  cumulative.	So in the above	example, first the configuration rela-
       tion defaults.base_features would enable	an initial  feature  set  with
       the  sparse_super,  filetype,  resize_inode, and	dir_index features en-
       abled.  Then configuration relation fs_types.ext4.features would	enable
       the  extents  and flex_bg features, and finally the configuration rela-
       tion 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 sub-
	      sections 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  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.

       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	 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.

       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 de-
	      fault extended options used by  mke2fs(8)	 on  a	per-filesystem
	      type basis.

       discard
	      This boolean relation specifies whether the mke2fs(8) should at-
	      tempt 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)

E2fsprogs version 1.42.9	 December 2013			mke2fs.conf(5)

NAME | DESCRIPTION | THE [defaults] STANZA | THE [fs_types] STANZA | THE [devices] STANZA | FILES | SEE ALSO

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