Provided by: xfsprogs_3.1.7_amd64 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.

                   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, 0 is assumed.

       -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 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.

       -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)