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mkfs.xfs(8)                 System Manager's Manual                mkfs.xfs(8)

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_op-
       tions  ]  [  -n  naming_options  ]  [  -p protofile ] [ -q ] [ -r real-
       time_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 us-
       ing the values found in the arguments of the command line.  It  is  in-
       voked automatically by mkfs(8) when it is given the -t xfs option.

       In its simplest (and most commonly used form), the size of the filesys-
       tem 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  be-
                     low).
              b - multiply  by filesystem block size (default = 4K, see -b op-
                     tion 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 explic-
       itly disable or enable the functionality.

OPTIONS
       -b block_size_options
              This option specifies the fundamental block size of the filesys-
              tem.  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
              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 fea-
                          ture, 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 archi-
                          tecture as some CPUs have hardware  acceleration  of
                          this algorithm.  Typically the overhead of calculat-
                          ing and checking the CRCs is not noticeable in  nor-
                          mal 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 in-
                          odes, allowing faster, more consistent inode alloca-
                          tion 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 gener-
                          ate a random UUID.

                   rmapbt=value
                          This option enables the creation of  a  reverse-map-
                          ping  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 map-
                          pings  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 filesys-
                          tems created with the (default) -m crc=1 option set.
                          When the option -m crc=0 is used, the  reverse  map-
                          ping 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 physi-
                          cal block, a reflink-capable XFS filesystem  removes
                          the uniqueness requirement, allowing up to four bil-
                          lion 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 logi-
                          cal-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 fea-
                          ture.  This feature is only available  for  filesys-
                          tems 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  re-
                          flink=0  option  to  mkfs.xfs to disable the reflink
                          feature.

       -d data_section_options
              These options specify the location, size, and  other  parameters
              of  the  data  section  of  the  filesystem. The valid data_sec-
              tion_options are:

                   agcount=value
                          This is used to specify  the  number  of  allocation
                          groups.  The  data  section of the filesystem is di-
                          vided into allocation groups to improve the  perfor-
                          mance 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 al-
                          location groups (default value is  scaled  automati-
                          cally based on the underlying device size).

                   agsize=value
                          This  is  an alternative to using the agcount subop-
                          tion. The value is the desired size of  the  alloca-
                          tion  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  automati-
                          cally adjusted to properly align with the stripe ge-
                          ometry.  The agcount and agsize suboptions are mutu-
                          ally 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 ei-
                          ther 0 or 1, with 1 signifying that the file is reg-
                          ular. This suboption is used only to make a filesys-
                          tem image. If the value is omitted  then  1  is  as-
                          sumed.

                   size=value
                          This  is  used  to specify the size of the data sec-
                          tion. This suboption is required if -d  file[=1]  is
                          given.  Otherwise, it is only needed if the filesys-
                          tem 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 subop-
                          tion 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 sub-
                          option 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, usu-
                          ally 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 de-
                          vice,  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 pro-
                          vides this information.

                   rtinherit=value
                          If  set, all inodes created by mkfs.xfs will be cre-
                          ated 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: direc-
              tory  data, for small directories; attribute data, for small at-
              tribute sets; symbolic link data, for small symbolic links;  the
              extent  list  for the file, for files with a small number of ex-
              tents; 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  can-
                          not 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 plat-
                          forms) 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 in-
                          ode 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  al-
                          locator  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 signifi-
                          cant 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  plat-
                          forms).

                          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 in-
                          ode alignment when the filesystem needs to be mount-
                          able by a version of IRIX that does not have the in-
                          ode 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 at-
                          tribute inline allocation policy to be used.  By de-
                          fault,  this is 2, which uses an efficient algorithm
                          for managing the available inline  inode  space  be-
                          tween 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  identi-
                          fiers. 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 alloca-
                          tion is enabled.  If the value is omitted, 1 is  as-
                          sumed.  Sparse  inode  allocation is disabled by de-
                          fault. This feature is only available  for  filesys-
                          tems 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 ex-
                          tents are large enough to accommodate a chunk of  64
                          inodes.  Without this feature enabled, inode alloca-
                          tions 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_op-
              tions 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 ex-
                          clusive.

                   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  perfor-
                          mance  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 au-
                          tomatically  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 automati-
                          cally selected if the log su suboption is specified.

                   lazy-count=value
                          This changes the method of logging  various  persis-
                          tent counters in the superblock.  Under metadata in-
                          tensive 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 persis-
                          tent  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_op-
              tions 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  directo-
                          ries  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 ver-
                          sion 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-insen-
                          sitive  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  de-
                          termine 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 func-
                          tionality 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 follow-
              ing 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 compati-
              bility: two numeric values must appear at  this  point  for  the
              proto  file to be correctly parsed, but their values are immate-
              rial 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 di-
              rectory. 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  speci-
              fied 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 regu-
              lar file, a block special file, a character special file, direc-
              tory files, named pipes (first-in, first out  files),  and  sym-
              bolic 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 speci-
              fied, 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  to-
              kens 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 num-
              bers 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  real-
              time_section_options are:

                   rtdev=device
                          This is used to specify the device which should con-
                          tain 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 vol-
                          ume containing the section.

                   noalign
                          This  option disables stripe size detection, enforc-
                          ing 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.

       -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  re-
              ally 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)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | SEE ALSO | BUGS