Provided by: xfsprogs_5.0.0-1ubuntu1_amd64 bug

NAME

       mkfs.xfs - construct an XFS filesystem

SYNOPSIS

       mkfs.xfs   [   -b   block_size_options   ]   [   -m   global_metadata_options   ]   [   -d
       data_section_options ] [ -f ] [ -i  inode_options  ]  [  -l  log_section_options  ]  [  -n
       naming_options  ]  [  -p  protofile  ]  [  -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 10MiB log located
       on the first partition on the second SCSI disk, use:

              mkfs.xfs -l logdev=/dev/sdb1,size=10m /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=10m and -l internal -l size=10m 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 first needs to be added to the command line.  Failure to specify the size of the
       units will result in illegal value errors when parameters are quantified in those units.

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

OPTIONS

       -b block_size_options
              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).

                          To specify any options on the  command  line  in  units  of  filesystem
                          blocks,  this  option  must  be  specified first so that the filesystem
                          block size is applied consistently to all options.

                          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
              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:

                   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.

                   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.

                   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  not  create  reference  count  btrees and
                          therefore will not 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.

       -d data_section_options
              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 children.

                   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.

                   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 logical volume device, mkfs.xfs  will
                          automatically query the logical volume for appropriate sunit and swidth
                          values.

                   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 set, all inodes  created  by  mkfs.xfs  will  be  created  with  the
                          realtime flag set.  Directories will pass on this flag to newly created
                          children.

                   projinherit=value
                          All inodes created by mkfs.xfs will be assigned this project quota  id.
                          Directories will pass on the project id to newly created children.

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

       -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
              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.

                          In the default inode allocation mode, inode blocks are chosen such that
                          inode numbers will not exceed 32 bits, which restricts the inode blocks
                          to the lower portion of the filesystem. The data block  allocator  will
                          avoid  these  low blocks to accommodate the specified maxpct, so a high
                          value may  result  in  a  filesystem  with  nothing  but  inodes  in  a
                          significant  portion  of  the  lower  blocks  of the filesystem.  (This
                          restriction is not present when the  filesystem  is  mounted  with  the
                          inode64 option on 64-bit platforms).

                          Setting the value to 0 means that essentially all of the filesystem can
                          become inode blocks, subject to inode32 restrictions.

                          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).

                   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.

                   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.)

                   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.

       -l log_section_options
              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.

                   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.

                   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.

       -n naming_options
              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.

       -p protofile
              If the optional -p 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.

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

       -r realtime_section_options
              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
              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.

                          To specify any options on the command line in units  of  sectors,  this
                          option  must  be  specified  first  so  that the sector size is applied
                          consistently to all options.

       -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.

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)