Provided by: xfsprogs_6.3.0-1ubuntu1_amd64 bug

NAME

       mkfs.xfs - construct an XFS filesystem

SYNOPSIS

       mkfs.xfs [ -b block_size_options ] [ -c config_file_options ] [ -m global_metadata_options
       ] [ -d data_section_options ] [ -f ] [ -i inode_options ] [ -l log_section_options ] [  -n
       naming_options  ]  [  -p  protofile_options  ] [ -q ] [ -r realtime_section_options ] [ -s
       sector_size_options ] [ -L label ] [ -N ] [ -K ] device
       mkfs.xfs -V

DESCRIPTION

       mkfs.xfs constructs an XFS filesystem by writing on a special file using the values  found
       in  the  arguments of the command line.  It is invoked automatically by mkfs(8) when it is
       given the -t xfs option.

       In its simplest (and most commonly used form), the size of the  filesystem  is  determined
       from  the  disk  driver.   As an example, to make a filesystem with an internal log on the
       first partition on the first SCSI disk, use:

              mkfs.xfs /dev/sda1

       The metadata log can be placed on another device to reduce the number of disk  seeks.   To
       create  a  filesystem  on  the  first  partition  on the first SCSI disk with a 100MiB log
       located on the first partition on the second SCSI disk, use:

              mkfs.xfs -l logdev=/dev/sdb1,size=100m /dev/sda1

       Each of the option elements in the argument list above can be  given  as  multiple  comma-
       separated  suboptions if multiple suboptions apply to the same option.  Equivalently, each
       main option can be given multiple  times  with  different  suboptions.   For  example,  -l
       internal,size=100m and -l internal -l size=100m are equivalent.

       In  the  descriptions  below,  sizes  are  given  in  sectors,  bytes,  blocks, kilobytes,
       megabytes, gigabytes, etc.  Sizes are treated as hexadecimal if  prefixed  by  0x  or  0X,
       octal if prefixed by 0, or decimal otherwise.  The following lists possible multiplication
       suffixes:
              s - multiply by sector size (default = 512, see -s option below).
              b - multiply by filesystem block size (default = 4K, see -b option below).
              k - multiply by one kilobyte (1,024 bytes).
              m - multiply by one megabyte (1,048,576 bytes).
              g - multiply by one gigabyte (1,073,741,824 bytes).
              t - multiply by one terabyte (1,099,511,627,776 bytes).
              p - multiply by one petabyte (1,024 terabytes).
              e - multiply by one exabyte (1,048,576 terabytes).

       When specifying parameters in units of sectors or filesystem blocks, the -s option or  the
       -b  option  may  be  used  to specify the size of the sector or block.  If the size of the
       block or sector is not specified, the default sizes (block: 4KiB, sector:  512B)  will  be
       used.

       Many feature options allow an optional argument of 0 or 1, to explicitly disable or enable
       the functionality.

       The correctness of the crc32c checksum implementation will be tested before formatting the
       filesystem.  If the test fails, the format will abort.

OPTIONS

       Options  may  be specified either on the command line or in a configuration file.  Not all
       command line options can be specified  in  configuration  files;  only  the  command  line
       options followed by a [section] label can be used in a configuration file.

       Options  that  can  be  used  in  configuration  files  are  grouped into related sections
       containing multiple options.  The command line options and  configuration  files  use  the
       same  option  sections  and  grouping.  Configuration file section names are listed in the
       command line option sections below.  Option names and values are the same for both command
       line and configuration file specification.

       Options  specified  are the combined set of command line parameters and configuration file
       parameters.  Duplicated options will result in a respecification error, regardless of  the
       location they were specified at.

       -c configuration_file_option
              This option specifies the files that mkfs configuration will be obtained from.  The
              valid configuration_file_option is:

                   options=name
                          The configuration options will be sourced from the  file  specified  by
                          the  name  option string.  This option can be use either an absolute or
                          relative  path  to  the  configuration  file  to   be   read.    Sample
                          configuration files can be found in /usr/share/xfsprogs/mkfs.

       -b block_size_options
       Section Name: [block]
              This  option  specifies  the  fundamental  block size of the filesystem.  The valid
              block_size_option is:

                   size=value
                          The filesystem block size is specified  with  a  value  in  bytes.  The
                          default  value  is  4096  bytes  (4  KiB),  the minimum is 512, and the
                          maximum is 65536 (64 KiB).

                          Although mkfs.xfs will accept any of these values and  create  a  valid
                          filesystem,  XFS  on  Linux can only mount filesystems with pagesize or
                          smaller blocks.

       -m global_metadata_options
       Section Name: [metadata]
              These options specify metadata format options  that  either  apply  to  the  entire
              filesystem  or  aren't  easily characterised by a specific functionality group. The
              valid global_metadata_options are:

                   bigtime=value
                          This option enables filesystems that can handle inode  timestamps  from
                          December  1901  to  July 2486, and quota timer expirations from January
                          1970 to July 2486.  The value is either 0 to disable the feature, or  1
                          to enable large timestamps.

                          If  this  feature  is  not  enabled,  the  filesystem  can  only handle
                          timestamps from December 1901 to January 2038, and  quota  timers  from
                          January 1970 to February 2106.

                          By  default, mkfs.xfs will enable this feature.  If the option -m crc=0
                          is used, the large timestamp feature is not supported and is disabled.

                   crc=value
                          This is used to create a filesystem  which  maintains  and  checks  CRC
                          information  in  all metadata objects on disk. The value is either 0 to
                          disable the feature, or 1 to enable the use of CRCs.

                          CRCs enable enhanced error detection due to hardware issues, whilst the
                          format  changes also improves crash recovery algorithms and the ability
                          of various tools to validate and repair metadata corruptions when  they
                          are  found.   The  CRC  algorithm  used  is  CRC32c, so the overhead is
                          dependent on CPU architecture as some CPUs have  hardware  acceleration
                          of  this algorithm.  Typically the overhead of calculating and checking
                          the CRCs is not noticeable in normal operation.

                          By default, mkfs.xfs will enable metadata CRCs.

                          Formatting a filesystem without CRCs selects the V4  format,  which  is
                          deprecated  and  will  be  removed  from  upstream  in  September 2030.
                          Distributors may choose to withdraw support for the V4  format  earlier
                          than  this  date.  Several other options, noted below, are only tunable
                          on V4 formats, and will be removed along with the V4 format itself.

                   finobt=value
                          This option enables the use of a separate free  inode  btree  index  in
                          each allocation group. The value is either 0 to disable the feature, or
                          1 to create a free inode btree in each allocation group.

                          The free inode btree mirrors the existing allocated inode  btree  index
                          which  indexes both used and free inodes. The free inode btree does not
                          index used inodes, allowing faster, more  consistent  inode  allocation
                          performance as filesystems age.

                          By  default,  mkfs.xfs  will  create  free inode btrees for filesystems
                          created with the (default) -m crc=1 option  set.  When  the  option  -m
                          crc=0  is  used,  the  free inode btree feature is not supported and is
                          disabled.

                   inobtcount=value
                          This option causes the filesystem to record the number of  blocks  used
                          by  the  inode  btree  and  the  free inode btree.  This can be used to
                          reduce mount times when the free inode btree is enabled.

                          By default, mkfs.xfs will enable this option.   This  feature  is  only
                          available for filesystems created with the (default) -m finobt=1 option
                          set.  When the option -m finobt=0 is  used,  the  inode  btree  counter
                          feature is not supported and is disabled.

                   uuid=value
                          Use  the  given  value  as  the  filesystem  UUID for the newly created
                          filesystem.  The default is to generate a random UUID.

                   rmapbt=value
                          This option enables the creation of a reverse-mapping  btree  index  in
                          each  allocation  group.  The value is either 0 to disable the feature,
                          or 1 to create the btree.

                          The reverse mapping btree maps filesystem blocks to the  owner  of  the
                          filesystem  block.  Most of the mappings will be to an inode number and
                          an offset, though there will also be mappings to  filesystem  metadata.
                          This secondary metadata can be used to validate the primary metadata or
                          to pinpoint exactly which data has been lost when a disk error occurs.

                          By default, mkfs.xfs will not  create  reverse  mapping  btrees.   This
                          feature is only available for filesystems created with the (default) -m
                          crc=1 option set. When the option -m crc=0 is used, the reverse mapping
                          btree feature is not supported and is disabled.

                   reflink=value
                          This  option  enables the use of a separate reference count btree index
                          in each allocation group. The value is either 0 to disable the feature,
                          or 1 to create a reference count btree in each allocation group.

                          The  reference  count  btree  enables  the  sharing of physical extents
                          between the data forks of different files, which is commonly  known  as
                          "reflink".  Unlike traditional Unix filesystems which assume that every
                          inode and logical block pair map to a unique physical block, a reflink-
                          capable  XFS filesystem removes the uniqueness requirement, allowing up
                          to four billion  arbitrary  inode/logical  block  pairs  to  map  to  a
                          physical  block.   If a program tries to write to a multiply-referenced
                          block in a file, the write will be redirected to a new block, and  that
                          file's  logical-to-physical  mapping  will  be changed to the new block
                          ("copy on write").  This  feature  enables  the  creation  of  per-file
                          snapshots  and  deduplication.  It is only available for the data forks
                          of regular files.

                          By default, mkfs.xfs will create reference count btrees  and  therefore
                          will  enable  the  reflink feature.  This feature is only available for
                          filesystems created with the (default) -m crc=1 option  set.  When  the
                          option  -m  crc=0  is  used,  the  reference count btree feature is not
                          supported and reflink is disabled.

                          Note: the filesystem DAX mount option ( -o dax ) is  incompatible  with
                          reflink-enabled  XFS  filesystems.   To  use  filesystem  DAX with XFS,
                          specify the -m reflink=0 option to  mkfs.xfs  to  disable  the  reflink
                          feature.

       -d data_section_options
       Section Name: [data]
              These  options specify the location, size, and other parameters of the data section
              of the filesystem. The valid data_section_options are:

                   agcount=value
                          This is used to specify the  number  of  allocation  groups.  The  data
                          section  of the filesystem is divided into allocation groups to improve
                          the  performance  of  XFS.  More  allocation  groups  imply  that  more
                          parallelism  can  be  achieved  when  allocating blocks and inodes. The
                          minimum allocation group size is 16 MiB; the maximum size is just under
                          1  TiB.   The  data  section  of  the  filesystem is divided into value
                          allocation groups (default value is scaled automatically based  on  the
                          underlying device size).

                   agsize=value
                          This is an alternative to using the agcount suboption. The value is the
                          desired size of the allocation group expressed in bytes (usually  using
                          the  m or g suffixes).  This value must be a multiple of the filesystem
                          block size, and must be at least 16MiB, and no more than 1TiB, and  may
                          be  automatically  adjusted to properly align with the stripe geometry.
                          The agcount and agsize suboptions are mutually exclusive.

                   cowextsize=value
                          Set the copy-on-write  extent  size  hint  on  all  inodes  created  by
                          mkfs.xfs.   The  value  must be provided in units of filesystem blocks.
                          If the value is zero, the default value (currently 32 blocks)  will  be
                          used.   Directories  will  pass  on  this hint to newly created regular
                          files and directories.

                   name=value
                          This can be used to specify the name of the special file containing the
                          filesystem. In this case, the log section must be specified as internal
                          (with a size, see the -l option below) and there can  be  no  real-time
                          section.

                   file[=value]
                          This  is used to specify that the file given by the name suboption is a
                          regular file. The value is either 0 or 1, with 1  signifying  that  the
                          file  is  regular.  This  suboption  is  used only to make a filesystem
                          image. If the value is omitted then 1 is assumed.

                   size=value
                          This is used to specify the size of the data section. This suboption is
                          required  if  -d file[=1] is given. Otherwise, it is only needed if the
                          filesystem should occupy less space than the size of the special file.

                          The data section must be at least 300MB in size.

                   sunit=value
                          This is used to specify the stripe unit for a RAID device or a  logical
                          volume.  The value has to be specified in 512-byte block units. Use the
                          su suboption to specify the stripe unit size in bytes.  This  suboption
                          ensures  that  data  allocations  will  be stripe unit aligned when the
                          current end of file is being extended and the file size is larger  than
                          512KiB. Also inode allocations and the internal log will be stripe unit
                          aligned.

                   su=value
                          This is an alternative to using sunit.  The su  suboption  is  used  to
                          specify  the stripe unit for a RAID device or a striped logical volume.
                          The value has to be specified in bytes,  (usually  using  the  m  or  g
                          suffixes). This value must be a multiple of the filesystem block size.

                   swidth=value
                          This is used to specify the stripe width for a RAID device or a striped
                          logical volume. The value has to be specified in 512-byte block  units.
                          Use  the  sw suboption to specify the stripe width size in bytes.  This
                          suboption is required if -d sunit has been specified and it has to be a
                          multiple of the -d sunit suboption.

                   sw=value
                          suboption  is an alternative to using swidth.  The sw suboption is used
                          to specify the stripe width  for  a  RAID  device  or  striped  logical
                          volume.  The  value  is  expressed  as a multiplier of the stripe unit,
                          usually the same as the number of stripe members in the logical  volume
                          configuration, or data disks in a RAID device.

                          When  a  filesystem  is  created  on  a  block  device,  mkfs.xfs  will
                          automatically query the block device for appropriate sunit  and  swidth
                          values if the block device and the filesystem size would be larger than
                          1GB.

                   noalign
                          This option disables  automatic  geometry  detection  and  creates  the
                          filesystem  without  stripe  geometry  alignment even if the underlying
                          storage device provides this information.

                   rtinherit=value
                          If value is set to 1, all inodes created by mkfs.xfs  will  be  created
                          with  the  realtime flag set.  The default is 0.  Directories will pass
                          on this flag to newly created regular files and directories.

                   projinherit=value
                          All inodes created by mkfs.xfs will be assigned the  project  quota  id
                          provided  in  value.   Directories will pass on the project id to newly
                          created regular files and directories.

                   extszinherit=value
                          All inodes created by mkfs.xfs will have this value  extent  size  hint
                          applied.   The  value  must  be provided in units of filesystem blocks.
                          Directories will pass on this hint to newly created regular  files  and
                          directories.

                   daxinherit=value
                          If  value  is  set to 1, all inodes created by mkfs.xfs will be created
                          with the DAX flag set.  The default is 0.   Directories  will  pass  on
                          this  flag to newly created regular files and directories.  By default,
                          mkfs.xfs will not enable DAX mode.

       -f     Force overwrite when an existing filesystem is detected on the device.  By default,
              mkfs.xfs  will not write to the device if it suspects that there is a filesystem or
              partition table on the device already.

       -i inode_options
       Section Name: [inode]
              This option specifies the inode size of the filesystem, and other inode  allocation
              parameters.   The  XFS  inode  contains a fixed-size part and a variable-size part.
              The variable-size part, whose  size  is  affected  by  this  option,  can  contain:
              directory  data,  for  small directories; attribute data, for small attribute sets;
              symbolic link data, for small symbolic links; the extent list  for  the  file,  for
              files  with  a  small  number  of  extents;  and  the root of a tree describing the
              location of extents for the file, for files with a large number of extents.

              The valid inode_options are:

                   size=value | perblock=value
                          The inode size is specified either as a value in bytes with size= or as
                          the  number  fitting in a filesystem block with perblock=.  The minimum
                          (and default) value is 256  bytes  without  crc,  512  bytes  with  crc
                          enabled.   The maximum value is 2048 (2 KiB) subject to the restriction
                          that the inode size cannot exceed one  half  of  the  filesystem  block
                          size.

                          XFS  uses  64-bit  inode  numbers  internally;  however,  the number of
                          significant bits in an inode number is affected by filesystem geometry.
                          In  practice,  filesystem  size  and  inode  size  are  the predominant
                          factors.  The Linux kernel (on 32  bit  hardware  platforms)  and  most
                          applications  cannot  currently  handle  inode  numbers greater than 32
                          significant bits, so if no inode size is given  on  the  command  line,
                          mkfs.xfs  will attempt to choose a size such that inode numbers will be
                          < 32 bits.  If an inode size  is  specified,  or  if  a  filesystem  is
                          sufficiently  large,  mkfs.xfs  will  warn  if  this  will create inode
                          numbers > 32 significant bits.

                   maxpct=value
                          This specifies the maximum percentage of space in the  filesystem  that
                          can  be  allocated  to inodes. The default value is 25% for filesystems
                          under 1TB, 5% for filesystems under 50TB and 1%  for  filesystems  over
                          50TB.

                          Setting the value to 0 means that essentially all of the filesystem can
                          become  inode  blocks  (subject  to  possible  inode32   mount   option
                          restrictions, see xfs(5) for details.)

                          This value can be modified with xfs_growfs(8).

                   align[=value]
                          This is used to specify that inode allocation is or is not aligned. The
                          value is either 0 or 1, with 1 signifying  that  inodes  are  allocated
                          aligned.   If  the  value is omitted, 1 is assumed. The default is that
                          inodes are aligned.  Aligned inode access is  normally  more  efficient
                          than  unaligned  access;  alignment must be established at the time the
                          filesystem is created, since inodes are allocated at that  time.   This
                          option  can  be  used  to  turn off inode alignment when the filesystem
                          needs to be mountable by a version of IRIX that does not have the inode
                          alignment feature (any release of IRIX before 6.2, and IRIX 6.2 without
                          XFS patches).

                          This option is only tunable on the deprecated V4 format.

                   attr=value
                          This is used to  specify  the  version  of  extended  attribute  inline
                          allocation  policy  to  be  used.  By default, this is 2, which uses an
                          efficient algorithm for  managing  the  available  inline  inode  space
                          between attribute and extent data.

                          The  previous  version  1,  which  has  fixed regions for attribute and
                          extent data, is kept for backwards  compatibility  with  kernels  older
                          than version 2.6.16.

                          This option is only tunable on the deprecated V4 format.

                   projid32bit[=value]
                          This  is  used  to enable 32bit quota project identifiers. The value is
                          either 0 or 1, with 1 signifying that 32bit projid are to  be  enabled.
                          If  the  value  is  omitted,  1  is  assumed.  (This default changed in
                          release version 3.2.0.)

                          This option is only tunable on the deprecated V4 format.

                   sparse[=value]
                          Enable sparse inode chunk allocation. The value is either 0 or 1,  with
                          1  signifying  that  sparse  allocation  is  enabled.   If the value is
                          omitted, 1 is assumed. Sparse inode allocation is disabled by  default.
                          This feature is only available for filesystems formatted with -m crc=1.

                          When enabled, sparse inode allocation allows the filesystem to allocate
                          smaller than the standard 64-inode chunk when free  space  is  severely
                          limited.  This  feature  is  useful for filesystems that might fragment
                          free space over time such that no free  extents  are  large  enough  to
                          accommodate  a  chunk of 64 inodes. Without this feature enabled, inode
                          allocations can fail with out of space errors under  severe  fragmented
                          free space conditions.

                   nrext64[=value]
                          Extend  maximum values of inode data and attr fork extent counters from
                          2^31 - 1 and 2^15 - 1 to 2^48 - 1 and 2^32 -  1  respectively.  If  the
                          value  is  omitted,  1 is assumed. This feature is disabled by default.
                          This feature is only available for filesystems formatted with -m crc=1.

              -l log_section_options
       Section Name: [log]
              These options specify the location, size, and other parameters of the  log  section
              of the filesystem. The valid log_section_options are:

                   agnum=value
                          If the log is internal, allocate it in this AG.

                   internal[=value]
                          This  is  used  to  specify that the log section is a piece of the data
                          section instead of being another device or logical volume. The value is
                          either 0 or 1, with 1 signifying that the log is internal. If the value
                          is omitted, 1 is assumed.

                   logdev=device
                          This is used to specify that the  log  section  should  reside  on  the
                          device  separate  from  the  data  section.  The  internal=1 and logdev
                          options are mutually exclusive.

                   size=value
                          This is used to specify the size of the log section.

                          If the log  is  contained  within  the  data  section  and  size  isn't
                          specified, mkfs.xfs will try to select a suitable log size depending on
                          the size  of  the  filesystem.   The  actual  logsize  depends  on  the
                          filesystem block size and the directory block size.

                          Otherwise,  the size suboption is only needed if the log section of the
                          filesystem should occupy less space than the size of the special  file.
                          The  value  is  specified  in  bytes or blocks, with a b suffix meaning
                          multiplication by the filesystem block size, as  described  above.  The
                          overriding   minimum   value   for  size  is  512  blocks.   With  some
                          combinations of filesystem block size, inode size, and directory  block
                          size, the minimum log size is larger than 512 blocks.

                          The log must be at least 64MB in size.  The log cannot be more than 2GB
                          in size.

                   version=value
                          This specifies the version of the log. The current default is 2,  which
                          allows  for  larger  log  buffer  sizes,  as well as supporting stripe-
                          aligned log writes (see the sunit and su options, below).

                          The previous version 1, which is limited to 32k log  buffers  and  does
                          not  support stripe-aligned writes, is kept for backwards compatibility
                          with very old 2.4 kernels.

                          This option is only tunable on the deprecated V4 format.

                   sunit=value
                          This specifies the alignment to be used for log writes. The  value  has
                          to  be  specified  in  512-byte  block  units.  Use the su suboption to
                          specify the log stripe unit size in bytes.  Log writes will be  aligned
                          on  this  boundary,  and rounded up to this boundary.  This gives major
                          improvements in performance on some  configurations  such  as  software
                          RAID5  when  the  sunit is specified as the filesystem block size.  The
                          equivalent byte value must be a multiple of the filesystem block  size.
                          Version 2 logs are automatically selected if the log sunit suboption is
                          specified.

                          The su suboption is an alternative to using sunit.

                   su=value
                          This is used to specify the log stripe. The value has to  be  specified
                          in  bytes,  (usually  using  the s or b suffixes). This value must be a
                          multiple  of  the  filesystem  block  size.    Version   2   logs   are
                          automatically selected if the log su suboption is specified.

                   lazy-count=value
                          This  changes  the method of logging various persistent counters in the
                          superblock.  Under metadata intensive  workloads,  these  counters  are
                          updated and logged frequently enough that the superblock updates become
                          a serialization point in the filesystem. The value can be either  0  or
                          1.

                          With  lazy-count=1,  the  superblock is not modified or logged on every
                          change of the persistent counters. Instead, enough information is  kept
                          in  other parts of the filesystem to be able to maintain the persistent
                          counter values without needed to keep them  in  the  superblock.   This
                          gives  significant  improvements in performance on some configurations.
                          The default value is 1 (on) so you must  specify  lazy-count=0  if  you
                          want to disable this feature for older kernels which don't support it.

                          This option is only tunable on the deprecated V4 format.

       -n naming_options
       Section Name: [naming]
              These  options  specify  the version and size parameters for the naming (directory)
              area of the filesystem. The valid naming_options are:

                   size=value
                          The directory block size is specified with a value in bytes.  The block
                          size  must be a power of 2 and cannot be less than the filesystem block
                          size.  The default size value for version 2 directories is  4096  bytes
                          (4 KiB), unless the filesystem block size is larger than 4096, in which
                          case the default value is the filesystem block  size.   For  version  1
                          directories the block size is the same as the filesystem block size.

                   version=value
                          The  naming  (directory)  version  value  can  be  either  2  or  'ci',
                          defaulting to 2  if  unspecified.   With  version  2  directories,  the
                          directory  block  size  can  be any power of 2 size from the filesystem
                          block size up to 65536.

                          The version=ci option  enables  ASCII  only  case-insensitive  filename
                          lookup  and  version 2 directories. Filenames are case-preserving, that
                          is, the names are stored  in  directories  using  the  case  they  were
                          created with.

                          Note: Version 1 directories are not supported.

                   ftype=value
                          This  feature  allows  the  inode  type  to  be stored in the directory
                          structure so that the readdir(3) and getdents(2) do not need to look up
                          the inode to determine the inode type.

                          The value is either 0 or 1, with 1 signifying that filetype information
                          will be stored in the directory structure.  The default value is 1.

                          When CRCs are enabled (the default), the ftype functionality is  always
                          enabled, and cannot be turned off.

                          In  other  words,  this  option  is  only  tunable on the deprecated V4
                          format.

       -p protofile_options
       Section Name: [proto]
              These options specify the protofile parameters for populating the filesystem.   The
              valid protofile_options are:

                   [file=]protofile
                          The  file=  prefix  is  not  required  for this CLI argument for legacy
                          reasons.  If specified as  a  config  file  directive,  the  prefix  is
                          required.

                          If the optional protofile argument is given, mkfs.xfs uses protofile as
                          a prototype file and takes its directions from that file.   The  blocks
                          and  inodes  specifiers  in  the  protofile  are provided for backwards
                          compatibility, but are otherwise unused.  The syntax of  the  protofile
                          is  defined by a number of tokens separated by spaces or newlines. Note
                          that the line numbers are not part of the syntax but are meant to  help
                          you in the following discussion of the file contents.

                               1       /stand/diskboot
                               2       4872 110
                               3       d--777 3 1
                               4       usr     d--777 3 1
                               5       sh      ---755 3 1 /bin/sh
                               6       ken     d--755 6 1
                               7               $
                               8       b0      b--644 3 1 0 0
                               9       c0      c--644 3 1 0 0
                               10      fifo    p--644 3 1
                               11      slink   l--644 3 1 /a/symbolic/link
                               12      :  This is a comment line
                               13      $
                               14      $

                          Line  1  is a dummy string.  (It was formerly the bootfilename.)  It is
                          present for backward compatibility; boot blocks are  not  used  on  SGI
                          systems.

                          Note  that  some string of characters must be present as the first line
                          of the proto file to cause it to be parsed correctly; the value of this
                          string is immaterial since it is ignored.

                          Line  2 contains two numeric values (formerly the numbers of blocks and
                          inodes).  These are also merely for backward compatibility: two numeric
                          values  must  appear  at  this point for the proto file to be correctly
                          parsed, but their values are immaterial since they are ignored.

                          The lines 3 through 11 specify the files and directories  you  want  to
                          include  in  this  filesystem. Line 3 defines the root directory. Other
                          directories and files that you want in the filesystem are indicated  by
                          lines  4  through  6  and lines 8 through 10. Line 11 contains symbolic
                          link syntax.

                          Notice the dollar sign ($) syntax on line 7. This  syntax  directs  the
                          mkfs.xfs  command  to  terminate  the  branch  of  the filesystem it is
                          currently on and then continue from the directory specified by the next
                          line,  in  this  case line 8.  It must be the last character on a line.
                          The colon on line 12 introduces a comment; all characters up until  the
                          following  newline are ignored.  Note that this means you cannot have a
                          file in a prototype file whose name contains a colon.  The $  on  lines
                          13 and 14 end the process, since no additional specifications follow.

                          File specifications provide the following:

                            * file mode
                            * user ID
                            * group ID
                            * the file's beginning contents

                          A  6-character  string defines the mode for a file. The first character
                          of this string defines the file type.  The  character  range  for  this
                          first  character  is  -bcdpl.   A  file  may be a regular file, a block
                          special file, a character special file, directory  files,  named  pipes
                          (first-in,  first out files), and symbolic links.  The second character
                          of the mode string is used to specify setuserID mode, in which case  it
                          is  u.   If setuserID mode is not specified, the second character is -.
                          The third  character  of  the  mode  string  is  used  to  specify  the
                          setgroupID  mode,  in  which  case  it is g.  If setgroupID mode is not
                          specified, the third character is -.  The remaining characters  of  the
                          mode  string  are a three digit octal number. This octal number defines
                          the owner, group, and other read, write, and  execute  permissions  for
                          the  file, respectively.  For more information on file permissions, see
                          the chmod(1) command.

                          Following the mode character string are two decimal number tokens  that
                          specify the user and group IDs of the file's owner.

                          In a regular file, the next token specifies the pathname from which the
                          contents and size of the file are copied.   In  a  block  or  character
                          special  file,  the next token are two decimal numbers that specify the
                          major and minor device numbers.  When a file is a  symbolic  link,  the
                          next token specifies the contents of the link.

                          When  the file is a directory, the mkfs.xfs command creates the entries
                          dot (.) and dot-dot (..) and then reads the  list  of  names  and  file
                          specifications  in  a  recursive  manner  for all of the entries in the
                          directory. A scan of the protofile is always terminated with the dollar
                          ( $ ) token.

                   slashes_are_spaces=value
                          If  set  to  1,  slashes  ("/")  in the first token of each line of the
                          protofile are converted to spaces.  This  enables  the  creation  of  a
                          filesystem  containing  filenames with spaces.  By default, this is set
                          to 0.

       -q     Quiet option. Normally mkfs.xfs prints the  parameters  of  the  filesystem  to  be
              constructed; the -q flag suppresses this.

       -r realtime_section_options
       Section Name: [realtime]
              These  options  specify  the  location, size, and other parameters of the real-time
              section of the filesystem. The valid realtime_section_options are:

                   rtdev=device
                          This is used to specify the device which should contain  the  real-time
                          section  of the filesystem.  The suboption value is the name of a block
                          device.

                   extsize=value
                          This is used to specify the size of the blocks in the real-time section
                          of  the  filesystem.  This  value  must be a multiple of the filesystem
                          block size. The minimum allowed size is the filesystem block size or  4
                          KiB  (whichever  is  larger);  the default size is the stripe width for
                          striped volumes or 64 KiB for non-striped volumes; the maximum  allowed
                          size  is 1 GiB. The real-time extent size should be carefully chosen to
                          match the parameters of the physical media used.

                   size=value
                          This is used to specify  the  size  of  the  real-time  section.   This
                          suboption  is  only  needed  if the real-time section of the filesystem
                          should occupy less space than the size  of  the  partition  or  logical
                          volume containing the section.

                   noalign
                          This option disables stripe size detection, enforcing a realtime device
                          with no stripe geometry.

       -s sector_size_options
       Section Name: [sector]
              This option specifies the fundamental sector size of  the  filesystem.   The  valid
              sector_size_option is:

                   size=value
                          The  sector  size  is  specified  with  a  value in bytes.  The default
                          sector_size is 512 bytes. The minimum value for sector size is 512; the
                          maximum  is  32768  (32 KiB). The sector_size must be a power of 2 size
                          and cannot be made larger than the filesystem block size.

       -L label
              Set the filesystem label.  XFS filesystem labels can be at most 12 characters long;
              if  label is longer than 12 characters, mkfs.xfs will not proceed with creating the
              filesystem.  Refer to the mount(8) and xfs_admin(8) manual entries  for  additional
              information.

       -N     Causes  the  file  system  parameters to be printed out without really creating the
              file system.

       -K     Do not attempt to discard blocks at mkfs time.

       -V     Prints the version number and exits.

Configuration File Format

       The configuration file uses a basic INI format to specify sections and  options  within  a
       section.   Section  and  option  names are case sensitive.  Section names must not contain
       whitespace.  Options are name-value pairs, ended by the  first  whitespace  in  the  line.
       Option  names  cannot  contain  whitespace.  Full line comments can be added by starting a
       line with a # symbol.  If values contain whitespace, then it must be quoted.

       The following example configuration file sets the block  size  to  4096  bytes,  turns  on
       reverse mapping btrees and sets the inode size to 2048 bytes.

       # Example mkfs.xfs configuration file

       [block]
       size=4k

       [metadata]
       rmapbt=1

       [inode]
       size=2048

SEE ALSO

       xfs(5), mkfs(8), mount(8), xfs_info(8), xfs_admin(8).

BUGS

       With a prototype file, it is not possible to specify hard links.

                                                                                      mkfs.xfs(8)