xenial (5) mke2fs.conf.5.gz

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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, 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 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.

       [options]
              Contains relations which influence how mke2fs behaves.

       [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 [options] STANZA

       The following relations are defined in the [options] stanza.

       proceed_delay
              If this relation is set to  a  positive  integer,  then  if  mke2fs  will  proceed  after  waiting
              proceed_delay  seconds,  after asking the user for permission to proceed, even if the user has not
              answered the question.  Defaults to 0, which means to wait until the user answers the question one
              way or another.

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.

       journal_location
              This relation specifies the location of the journal.

       num_backup_sb
              This  relation  indicates  whether  file  systems with the sparse_super2 feature enabled should be
              created with 0, 1, or 2 backup superblocks.

       packed_meta_blocks
              This boolean relation specifes whether the allocation bitmaps, inode table, and journal should  be
              located at the beginning of the file system.

       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)

       make_hugefiles
              This boolean relation enables the creation of pre-allocated files as part of formatting  the  file
              system.

       hugefiles_uid
              This  relation  controls  the  user  ownership for all of the files and directories created by the
              make_hugefiles feature.

       hugefiles_gid
              This relation controls the group ownership for all of the files and  directories  created  by  the
              make_hugefiles feature.

       hugefiles_umask
              This  relation  specifies  the  umask  used  when  creating  the  files  and  directories  by  the
              make_hugefiles feature.

       num_hugefiles
              This relation specifies the number of  huge  files  to  be  created.   If  this  relation  is  not
              specified,  or  is  set  to zero, and the hugefiles_size relation is non-zero, then make_hugefiles
              will create as many huge files as can fit to fill the entire file system.

       hugefiles_slack
              This relation specifies how much space should be reserved for other files.

       hugefiles_size
              This relation specifies the size of the huge files.   If  this  relation  is  not  specified,  the
              default is to fill the entire file system.

       hugefiles_align
              This  relation  specifies the alignment for the start block of the huge files.  It also forces the
              size of huge files to be a  multiple  of  the  requested  alignment.   If  this  relation  is  not
              specified, no alignment requirement will be imposed on the huge files.

       hugefiles_align_disk
              Thie  relations  specifies  whether  the alignment should be relative to the beginning of the hard
              drive (assuming that the starting offset of the partition is available to  mke2fs).   The  default
              value is false, which if will cause hugefile alignment to be relative to the beginning of the file
              system.

       hugefiles_name
              This relation specifies the base file name for the huge files.

       hugefiles_digits
              This relation specifies the (zero-padded) width of the field for the huge file number.

       zero_hugefiles
              This boolean relation specifies whether or not zero blocks will be written to the hugefiles  while
              mke2fs(8)  is  creating  them.  By default, zero blocks will be written to the huge files to avoid
              stale data from being made available to potentially untrusted user  programs,  unless  the  device
              supports  a  discard/trim  operation  which  will  take  care  of  zeroing  the device blocks.  By
              zero_hugefiles to false, this step will always be skipped, which can be useful if it is known that
              the  disk  has  been  previously erased, or if the user programs that will have access to the huge
              files are trusted to not reveal stale data.

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)