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    Command:

    mkfs.xfs

    
    
    

    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 filesys-
           tem  is  determined  from  the  disk  driver.  As an example, to make a
           filesystem with an internal log on the first  partition  on  the  first
           SCSI disk, use:
    
                  mkfs.xfs /dev/sda1
    
           The  metadata  log can be placed on another device to reduce the number
           of disk seeks.  To create a filesystem on the first  partition  on  the
           first  SCSI  disk with a 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 filesys-
                  tem.  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
                              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 subop-
                              tion. The value is the desired size of  the  alloca-
                              tion  group  expressed in bytes (usually using the m
                              or g suffixes).  This value must be  a  multiple  of
                              the  filesystem  block  size,  and  must be at least
                              16MiB, and no more than 1TiB, and may  be  automati-
                              cally  adjusted  to  properly  align with the stripe
                              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  sec-
                              tion.  This  suboption is required if -d file[=1] is
                              given. Otherwise, it is only needed if the  filesys-
                              tem  should  occupy  less space than the size of the
                              special file.
    
                       sunit=value
                              This is used to specify the stripe unit for  a  RAID
                              device  or  a  logical  volume.  The value has to be
                              specified in 512-byte block units. Use the su subop-
                              tion  to specify the stripe unit size in bytes. This
                              suboption ensures  that  data  allocations  will  be
                              stripe  unit aligned when the current end of file is
                              being extended and the  file  size  is  larger  than
                              512KiB.  Also inode allocations and the internal log
                              will be stripe unit aligned.
    
                       su=value
                              sunit suboption.
    
                       sw=value
                              suboption is an alternative to using swidth.  The sw
                              suboption is used to specify the stripe width for  a
                              RAID  device or striped logical volume. The value is
                              expressed as a multiplier of the stripe  unit,  usu-
                              ally the same as the number of stripe members in the
                              logical volume configuration, or  data  disks  in  a
                              RAID device.
    
                              When  a  filesystem  is  created on a logical volume
                              device, mkfs.xfs will automatically query the  logi-
                              cal  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: direc-
                  tory  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)  sub-
                              ject  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 plat-
                              forms) and most applications cannot currently handle
                              inode numbers greater than 32 significant  bits,  so
                              if  no  inode  size  is  given  on the command line,
                              mkfs.xfs will attempt to choose  a  size  such  that
                              inode  numbers  will be < 32 bits.  If an inode size
                              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  signifi-
                              cant  portion of the lower blocks of the filesystem.
                              (This restriction is not present when the filesystem
                              is  mounted  with the inode64 option on 64-bit plat-
                              forms).
    
                              Setting the value to 0 means that essentially all of
                              the  filesystem  can become inode blocks, subject to
                              inode32 restrictions.
    
                              This value can be modified with xfs_growfs(8).
    
                       align[=value]
                              This is used to specify that inode allocation is  or
                              is  not  aligned. The value is either 0 or 1, with 1
                              signifying that inodes are  allocated  aligned.   If
                              the  value  is omitted, 1 is assumed. The default is
                              that inodes are aligned.  Aligned  inode  access  is
                              normally   more  efficient  than  unaligned  access;
                              alignment  must  be  established  at  the  time  the
                              filesystem is created, since inodes are allocated at
                              that time.  This option can  be  used  to  turn  off
                              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  algo-
                              rithm  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 identi-
                              fiers. 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_sec-
                  tion_options are:
                       size=value
                              This is used to specify the size of the log section.
    
                              If the log is contained within the data section  and
                              size  isn't specified, mkfs.xfs will try to select a
                              suitable log size  depending  on  the  size  of  the
                              filesystem.   The  actual  logsize  depends  on  the
                              filesystem block size and the directory block  size.
    
                              Otherwise,  the size suboption is only needed if the
                              log section of the  filesystem  should  occupy  less
                              space  than  the size of the special file. The value
                              is specified in bytes or blocks,  with  a  b  suffix
                              meaning multiplication by the filesystem block size,
                              as described above. The overriding minimum value for
                              size  is  512  blocks.   With  some  combinations of
                              filesystem block size,  inode  size,  and  directory
                              block  size, the minimum log size is larger than 512
                              blocks.
    
                       version=value
                              This specifies the version of the log.  The  current
                              default  is  2,  which  allows for larger log buffer
                              sizes, as  well  as  supporting  stripe-aligned  log
                              writes (see the sunit and su options, below).
    
                              The  previous version 1, which is limited to 32k log
                              buffers and does not support stripe-aligned  writes,
                              is  kept  for  backwards compatibility with very old
                              2.4 kernels.
    
                       sunit=value
                              This specifies the alignment  to  be  used  for  log
                              writes.  The  value  has to be specified in 512-byte
                              block units. Use the su suboption to specify the log
                              stripe  unit  size  in  bytes.   Log  writes will be
                              aligned on this boundary, and  rounded  up  to  this
                              boundary.   This gives major improvements in perfor-
                              mance on some configurations such as software  RAID5
                              when  the sunit is specified as the filesystem block
                              size.  The equivalent byte value must be a  multiple
                              of  the  filesystem  block  size. Version 2 logs are
                              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 automati-
                              tent  counter  values without needed to keep them in
                              the superblock.  This gives significant improvements
                              in  performance on some configurations.  The default
                              value is 1 (on) so you must specify lazy-count=0  if
                              you  want  to disable this feature for older kernels
                              which don't support it.
    
           -n naming_options
                  These options specify the version and size  parameters  for  the
                  naming  (directory)  area  of  the  filesystem.  The  valid nam-
                  ing_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 directo-
                              ries the block size is the same  as  the  filesystem
                              block size.
    
                       version=value
                              The naming (directory) version value can be either 2
                              or 'ci', defaulting to 2 if unspecified.  With  ver-
                              sion  2 directories, the directory block size can be
                              any power of 2 size from the filesystem  block  size
                              up to 65536.
    
                              The version=ci option enables ASCII only case-insen-
                              sitive filename lookup and  version  2  directories.
                              Filenames  are  case-preserving,  that is, the names
                              are stored in directories using the case  they  were
                              created with.
    
                              Note: Version 1 directories are not supported.
    
           -p protofile
                  If  the  optional  -p protofile argument is given, mkfs.xfs uses
                  protofile as a prototype file and takes its directions from that
                  file.   The  blocks  and  inodes specifiers in the protofile are
                  provided for backwards compatibility, but are otherwise  unused.
                  The  syntax  of  the  protofile is defined by a number of tokens
                  separated by spaces or newlines. Note that the line numbers  are
                  not  part of the syntax but are meant to help you in the follow-
                  ing discussion of the file contents.
    
                       1       /stand/diskboot
                       2       4872 110
                       3       d--777 3 1
    
                  used on SGI systems.
    
                  Note that some string of characters must be present as the first
                  line  of  the proto file to cause it to be parsed correctly; the
                  value of this string is immaterial since it is ignored.
    
                  Line 2 contains two numeric  values  (formerly  the  numbers  of
                  blocks and inodes).  These are also merely for backward compati-
                  bility: two numeric values must appear at  this  point  for  the
                  proto  file to be correctly parsed, but their values are immate-
                  rial since they are ignored.
    
                  The lines 3 through 11 specify the  files  and  directories  you
                  want  to  include  in  this  filesystem. Line 3 defines the root
                  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  speci-
                  fied by the next line, in this case line 8.  It must be the last
                  character on a line.  The colon on line 12 introduces a comment;
                  all characters up until the following newline are ignored.  Note
                  that this means you cannot have a file in a prototype file whose
                  name  contains  a  colon.  The $ on lines 13 and 14 end the pro-
                  cess, since no additional specifications follow.
    
                  File specifications provide the following:
    
                    * file mode
                    * user ID
                    * group ID
                    * the file's beginning contents
    
                  A 6-character string defines the mode  for  a  file.  The  first
                  character  of  this  string defines the file type. The character
                  range for this first character is -bcdpl.  A file may be a regu-
                  lar file, a block special file, a character special file, direc-
                  tory files, named pipes (first-in, first out  files),  and  sym-
                  bolic links.  The second character of the mode string is used to
                  specify setuserID mode, in which case it  is  u.   If  setuserID
                  mode  is  not  specified,  the second character is -.  The third
                  character of the mode string is used to specify  the  setgroupID
                  mode,  in  which case it is g.  If setgroupID mode is not speci-
                  fied, the third character is -.  The remaining characters of the
                  mode  string  are  a three digit octal number. This octal number
                  defines the owner, group, and other  read,  write,  and  execute
                  permissions for the file, respectively.  For more information on
                  file permissions, see the chmod(1) command.
    
                  terminated with the dollar ( $ ) token.
    
           -q     Quiet  option.  Normally  mkfs.xfs  prints the parameters of the
                  filesystem to be constructed; the -q flag suppresses this.
    
           -r realtime_section_options
                  These options specify the location, size, and  other  parameters
                  of  the  real-time  section  of  the filesystem. The valid real-
                  time_section_options are:
    
                       rtdev=device
                              This is used to specify the device which should con-
                              tain  the  real-time section of the filesystem.  The
                              suboption value is the name of a block device.
    
                       extsize=value
                              This is used to specify the size of  the  blocks  in
                              the  real-time section of the filesystem. This value
                              must be a multiple of the filesystem block size. The
                              minimum allowed size is the filesystem block size or
                              4 KiB (whichever is larger); the default size is the
                              stripe  width for striped volumes or 64 KiB for non-
                              striped volumes; the maximum allowed size is 1  GiB.
                              The real-time extent size should be carefully chosen
                              to match the parameters of the physical media  used.
    
                       size=value
                              This  is  used  to specify the size of the real-time
                              section.  This suboption is only needed if the real-
                              time  section  of  the filesystem should occupy less
                              space than the size of the partition or logical vol-
                              ume containing the section.
    
           -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.
    
    
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