Home : Computers : Linux : Man Pages : mkfs.xfs

mkfs.xfs


SYNOPSIS

       mkfs.xfs  [  -b  block_size  ]  [  -m  global_metadata_options  ]  [ -d
       data_section_options ] [ -f ]  [  -i  inode_options  ]  [  -l  log_sec-
       tion_options ] [ -n naming_options ] [ -p protofile ] [ -q ] [ -r real-
       time_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 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
                   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 fea-
                          ture, 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 archi-
                          tecture as some CPUs have hardware  acceleration  of
                          this algorithm.  Typically the overhead of calculat-
                          ing and checking the CRCs is not noticeable in  nor-
                          mal 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 allo-
                          cation performance as filesystems age.

                          By default, mkfs.xfs  will  not  create  free  inode
                          btrees  for filesystems.  This is for backwards com-
                          patibility with older RHEL7 kernels.   If  the  free
                          inode btree is enabled, older RHEL7 kernels will not
                          be able to mount the created filesystem.   When  the
                          option  -m  crc=0 is used, the free inode btree fea-
                          ture 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 gener-
                          ate 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_sec-
              tion_options are:

                   agcount=value
                          This is used to specify  the  number  of  allocation
                          groups.  The  data  section  of  the  filesystem  is
                          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.
                          device, mkfs.xfs will automatically query the  logi-
                          cal 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 pro-
                          vides 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: 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 minimum (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 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
                          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, 1 is assumed.  (This default changed in
                          release version 3.2.0.)

                   sparse[=value]
                          Enable sparse inode chunk allocation.  This  experi-
                          mental option is not available in RHEL7.

       -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:

                          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.
                          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.

                   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  func-
                          tionality is always enabled. This feature can not be
                          turned off for such filesystem configurations.

                   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-

              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.

                   noalign
                          This option disables stripe size detection,  enforc-
                          ing 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
              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)
Subscribe to us on YouTube