Provided by: xfsprogs_4.3.0+nmu1ubuntu1_i386 bug

NAME

       mkfs.xfs - construct an XFS filesystem

SYNOPSIS

       mkfs.xfs  [  -b  block_size  ]  [  -m  global_metadata_options  ]  [ -d
       data_section_options  ]  [  -f  ]   [   -i   inode_options   ]   [   -l
       log_section_options  ]  [ -n naming_options ] [ -p protofile ] [ -q ] [
       -r realtime_section_options ] [ -s sector_size ] [ -L label ] [ -N ]  [
       -K ] device
       mkfs.xfs -V

DESCRIPTION

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

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

              mkfs.xfs /dev/sda1

       The metadata log can be placed on another device to reduce  the  number
       of  disk  seeks.   To create a filesystem on the first partition on the
       first SCSI disk with a 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.

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

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

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

                          By default, mkfs.xfs will enable metadata CRCs.

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

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

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

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

       -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.

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

       -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 minimum (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
                          sufficiently large, mkfs.xfs will warn if this  will
                          create inode numbers > 32 significant bits.

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

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

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

                          This value can be modified with xfs_growfs(8).

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

                          The su suboption is an alternative to using sunit.

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

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

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

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

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

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

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

                          Note: Version 1 directories are not supported.

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

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

                          When  CRCs  are  enabled  via  -m  crc=1,  the ftype
                          functionality is always enabled.  This  feature  can
                          not    be    turned    off   for   such   filesystem
                          configurations.

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

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

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

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

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

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

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

              File specifications provide the following:

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

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

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

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

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

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

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

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

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

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

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

       -s sector_size
              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.

       -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)