Provided by: xfsprogs_3.1.0ubuntu1_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 ] [ -K ] 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.

       -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% 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.

       -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  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 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 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 | 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 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.

       -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.

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

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)