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mkfs.xfs(8)							   mkfs.xfs(8)

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 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
	      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_sec‐
	      tion_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 per‐
			  formance 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	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
			  This	is an alternative to using sunit.  The su sub‐
			  option 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, 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
			  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 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:

		   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  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‐
			  cally selected if the log su suboption is specified.

		   lazy-count=value
			  This changes the method of logging  various  persis‐
			  tent	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 persis‐
			  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
		   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 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
	      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 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.

	      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 num‐
	      bers 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	 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.

       -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)
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