Provided by: xfsprogs_2.9.4-2_i386 bug

NAME

       mkfs.xfs - construct an XFS filesystem

SYNOPSIS

       mkfs.xfs  [  -b  block_size  ]  [ -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 ] [
       -L label ] [ -N ] device

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 10000 block log located on the first partition
       on the second SCSI disk, use:

              mkfs.xfs -l logdev=/dev/sdb1,size=10000b /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=10000b
       and -l internal -l size=10000b 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).

OPTIONS

       -b block_size_options
              This   option  specifies  the  fundamental  block  size  of  the
              filesystem.  The  valid  block_size_options  are:  log=value  or
              size=value  and  only  one  can  be supplied.  The block size is
              specified either as a base two logarithm value with log=, or  in
              bytes  with size=.  The default value is 4096 bytes (4 KiB), the
              minimum is 512, and the maximum is 65536 (64 KiB).  XFS on Linux
              currently only supports pagesize or smaller blocks.

       -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.

                   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.

                   unwritten[=value]
                          This is used to specify  whether  unwritten  extents
                          are  flagged as such, or not.  The value is either 0
                          or  1,  with  1  signifying  that  unwritten  extent
                          flagging should occur.  If the suboption is omitted,
                          unwritten extent flagging is enabled.  If  unwritten
                          extents  are  flagged,  filesystem write performance
                          will be negatively affected  for  preallocated  file
                          extents,  since  extra  filesystem  transactions are
                          required to convert extent flags for  the  range  of
                          the file written.  This suboption should be disabled
                          if the filesystem needs  to  be  used  on  operating
                          system  versions  which  do not support the flagging
                          capability.

       -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 | log=value | perblock=value
                          The inode size is specified either  as  a  value  in
                          bytes  with  size=,  a base two logarithm value with
                          log=, or as the number fitting in a filesystem block
                          with  perblock=.  The mininum (and default) value is
                          256 bytes.   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 sufficently
                          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%. Setting the value to 0 means
                          that essentially all of the  filesystem  can  become
                          inode blocks.

                   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 zero.  Once extended attributes are
                          used for the first time, the version will be set  to
                          either one or two.  The current version (two) uses a
                          more efficient algorithm for managing the  available
                          inline  inode  space than version one does, however,
                          for  backward  compatibility  reasons  (and  in  the
                          absence  of  the  attr=2  mkfs  option, or the attr2
                          mount option),  version  one  will  be  selected  by
                          default   when   attributes  are  first  used  on  a
                          filesystem.

       -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:

                   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 value  is
                          either  1  or  2.  Specifying  version=2 enables the
                          sunit suboption,  and  allows  the  logbsize  to  be
                          increased   beyond   32K.    Version   2   logs  are
                          automatically selected  if  a  log  stripe  unit  is
                          specified.  See sunit and su suboptions, below.

                   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 serialisation 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  0 (off) so you must specify
                          lazy-count=1  if  you  want  to  make  use  of  this
                          feature.

       -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 | log=value
                          The  block  size  is  specified either as a value in
                          bytes with size=, or as a base two  logarithm  value
                          with  log=.   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 1
                          or  2, 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.

       -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.

       -s sector_size
              This  option  specifies  the  fundamental  sector  size  of  the
              filesystem.  The sector_size is specified either as a  value  in
              bytes  with  size=value  or  as  a base two logarithm value with
              log=value.  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.

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)