mkfs.xfs(8) — Linux manual page

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mkfs.xfs(8)              System Manager's Manual             mkfs.xfs(8)

NAME         top

       mkfs.xfs - construct an XFS filesystem

SYNOPSIS         top

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

DESCRIPTION         top

       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 10MiB log located on the
       first partition on the second SCSI disk, use:

              mkfs.xfs -l logdev=/dev/sdb1,size=10m /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=10m and -l internal -l size=10m 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).

       When specifying parameters in units of sectors or filesystem
       blocks, the -s option or the -b option may be used to specify the
       size of the sector or block.  If the size of the block or sector
       is not specified, the default sizes (block: 4KiB, sector: 512B)
       will be used.

       Many feature options allow an optional argument of 0 or 1, to
       explicitly disable or enable the functionality.

OPTIONS         top

       Options may be specified either on the command line or in a
       configuration file.  Not all command line options can be
       specified in configuration files; only the command line options
       followed by a [section] label can be used in a configuration
       file.

       Options that can be used in configuration files are grouped into
       related sections containing multiple options.  The command line
       options and configuration files use the same option sections and
       grouping.  Configuration file section names are listed in the
       command line option sections below.  Option names and values are
       the same for both command line and configuration file
       specification.

       Options specified are the combined set of command line parameters
       and configuration file parameters.  Duplicated options will
       result in a respecification error, regardless of the location
       they were specified at.

       -c configuration_file_option
              This option specifies the files that mkfs configuration
              will be obtained from.  The valid
              configuration_file_option is:

                   options=name
                          The configuration options will be sourced from
                          the file specified by the name option string.
                          This option can be use either an absolute or
                          relative path to the configuration file to be
                          read.

       -b block_size_options
       Section Name: [block]
              This option specifies the fundamental block size of the
              filesystem.  The valid block_size_option is:

                   size=value
                          The filesystem block size is specified with a
                          value in bytes. The default value is 4096
                          bytes (4 KiB), the minimum is 512, and the
                          maximum is 65536 (64 KiB).

                          Although mkfs.xfs will accept any of these
                          values and create a valid filesystem, XFS on
                          Linux can only mount filesystems with pagesize
                          or smaller blocks.

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

                   bigtime=value
                          This option enables filesystems that can
                          handle inode timestamps from December 1901 to
                          July 2486, and quota timer expirations from
                          January 1970 to July 2486.  The value is
                          either 0 to disable the feature, or 1 to
                          enable large timestamps.

                          If this feature is not enabled, the filesystem
                          can only handle timestamps from December 1901
                          to January 2038, and quota timers from January
                          1970 to February 2106.

                          By default, mkfs.xfs will not enable this
                          feature.  If the option -m crc=0 is used, the
                          large timestamp feature is not supported and
                          is disabled.

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

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

                          By default, mkfs.xfs will enable metadata
                          CRCs.

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

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

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

                   inobtcount=value
                          This option causes the filesystem to record
                          the number of blocks used by the inode btree
                          and the free inode btree.  This can be used to
                          reduce mount times when the free inode btree
                          is enabled.

                          By default, mkfs.xfs will not enable this
                          option.  This feature is only available for
                          filesystems created with the (default) -m
                          finobt=1 option set.  When the option -m
                          finobt=0 is used, the inode btree counter
                          feature is not supported and is disabled.

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

                   rmapbt=value
                          This option enables the creation of a reverse-
                          mapping btree index in each allocation group.
                          The value is either 0 to disable the feature,
                          or 1 to create the btree.

                          The reverse mapping btree maps filesystem
                          blocks to the owner of the filesystem block.
                          Most of the mappings will be to an inode
                          number and an offset, though there will also
                          be mappings to filesystem metadata.  This
                          secondary metadata can be used to validate the
                          primary metadata or to pinpoint exactly which
                          data has been lost when a disk error occurs.

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

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

                          The reference count btree enables the sharing
                          of physical extents between the data forks of
                          different files, which is commonly known as
                          "reflink".  Unlike traditional Unix
                          filesystems which assume that every inode and
                          logical block pair map to a unique physical
                          block, a reflink-capable XFS filesystem
                          removes the uniqueness requirement, allowing
                          up to four billion arbitrary inode/logical
                          block pairs to map to a physical block.  If a
                          program tries to write to a multiply-
                          referenced block in a file, the write will be
                          redirected to a new block, and that file's
                          logical-to-physical mapping will be changed to
                          the new block ("copy on write").  This feature
                          enables the creation of per-file snapshots and
                          deduplication.  It is only available for the
                          data forks of regular files.

                          By default, mkfs.xfs will create reference
                          count btrees and therefore will enable the
                          reflink feature.  This feature is only
                          available for filesystems created with the
                          (default) -m crc=1 option set. When the option
                          -m crc=0 is used, the reference count btree
                          feature is not supported and reflink is
                          disabled.

                          Note: the filesystem DAX mount option ( -o dax
                          ) is incompatible with reflink-enabled XFS
                          filesystems.  To use filesystem DAX with XFS,
                          specify the -m reflink=0 option to mkfs.xfs to
                          disable the reflink feature.

       -d data_section_options
       Section Name: [data]
              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.

                   cowextsize=value
                          Set the copy-on-write extent size hint on all
                          inodes created by mkfs.xfs.  The value must be
                          provided in units of filesystem blocks.  If
                          the value is zero, the default value
                          (currently 32 blocks) will be used.
                          Directories will pass on this hint to newly
                          created regular files and directories.

                   name=value
                          This can be used to specify the name of the
                          special file containing the filesystem. In
                          this case, the log section must be specified
                          as internal (with a size, see the -l option
                          below) and there can be no real-time section.

                   file[=value]
                          This is used to specify that the file given by
                          the name suboption is a regular file. The
                          value is either 0 or 1, with 1 signifying that
                          the file is regular. This suboption is used
                          only to make a filesystem image. If the value
                          is omitted then 1 is assumed.

                   size=value
                          This is used to specify the size of the data
                          section. This suboption is required if -d
                          file[=1] is given. Otherwise, it is only
                          needed if the filesystem should occupy less
                          space than the size of the special file.

                   sunit=value
                          This is used to specify the stripe unit for a
                          RAID device or a logical volume. The value has
                          to be specified in 512-byte block units. Use
                          the su suboption to specify the stripe unit
                          size in bytes. This suboption ensures that
                          data allocations will be stripe unit aligned
                          when the current end of file is being extended
                          and the file size is larger than 512KiB. Also
                          inode allocations and the internal log will be
                          stripe unit aligned.

                   su=value
                          This is an alternative to using sunit.  The su
                          suboption is used to specify the stripe unit
                          for a RAID device or a striped logical volume.
                          The value has to be specified in bytes,
                          (usually using the m or g suffixes). This
                          value must be a multiple of the filesystem
                          block size.

                   swidth=value
                          This is used to specify the stripe width for a
                          RAID device or a striped logical volume. The
                          value has to be specified in 512-byte block
                          units. Use the sw suboption to specify the
                          stripe width size in bytes.  This suboption is
                          required if -d sunit has been specified and it
                          has to be a multiple of the -d sunit
                          suboption.

                   sw=value
                          suboption is an alternative to using swidth.
                          The sw suboption is used to specify the stripe
                          width for a RAID device or striped logical
                          volume. The value is expressed as a multiplier
                          of the stripe unit, usually the same as the
                          number of stripe members in the logical volume
                          configuration, or data disks in a RAID device.

                          When a filesystem is created on a logical
                          volume device, mkfs.xfs will automatically
                          query the logical volume for appropriate sunit
                          and swidth values.

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

                   rtinherit=value
                          If value is set to 1, all inodes created by
                          mkfs.xfs will be created with the realtime
                          flag set.  The default is 0.  Directories will
                          pass on this flag to newly created regular
                          files and directories.

                   projinherit=value
                          All inodes created by mkfs.xfs will be
                          assigned the project quota id provided in
                          value.  Directories will pass on the project
                          id to newly created regular files and
                          directories.

                   extszinherit=value
                          All inodes created by mkfs.xfs will have this
                          value extent size hint applied.  The value
                          must be provided in units of filesystem
                          blocks.  Directories will pass on this hint to
                          newly created regular files and directories.

                   daxinherit=value
                          If value is set to 1, all inodes created by
                          mkfs.xfs will be created with the DAX flag
                          set.  The default is 0.  Directories will pass
                          on this flag to newly created regular files
                          and directories.  By default, mkfs.xfs will
                          not enable DAX mode.

       -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
       Section Name: [inode]
              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 | perblock=value
                          The inode size is specified either as a value
                          in bytes with size= or as the number fitting
                          in a filesystem block with perblock=.  The
                          minimum (and default) value is 256 bytes
                          without crc, 512 bytes with crc enabled.  The
                          maximum value is 2048 (2 KiB) subject to the
                          restriction that the inode size cannot exceed
                          one half of the filesystem block size.

                          XFS uses 64-bit inode numbers internally;
                          however, the number of significant bits in an
                          inode number is affected by filesystem
                          geometry.  In practice, filesystem size and
                          inode size are the predominant factors.  The
                          Linux kernel (on 32 bit hardware platforms)
                          and most applications cannot currently handle
                          inode numbers greater than 32 significant
                          bits, so if no inode size is given on the
                          command line, mkfs.xfs will attempt to choose
                          a size such that inode numbers will be < 32
                          bits.  If an inode size is specified, or if a
                          filesystem is sufficiently large, mkfs.xfs
                          will warn if this will create inode numbers >
                          32 significant bits.

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

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

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

                          This value can be modified with xfs_growfs(8).

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

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

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

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

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

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

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

                   agnum=value
                          If the log is internal, allocate it in this
                          AG.

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

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

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

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

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

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

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

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

                          The su suboption is an alternative to using
                          sunit.

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

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

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

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

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

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

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

                          Note: Version 1 directories are not supported.

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

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

                          When CRCs are enabled (the default), the ftype
                          functionality is always enabled, and cannot be
                          turned off.

       -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
       Section Name: [realtime]
              These options specify the location, size, and other
              parameters of the real-time section of the filesystem. The
              valid realtime_section_options are:

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

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

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

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

       -s sector_size_options
       Section Name: [sector]
              This option specifies the fundamental sector size of the
              filesystem.  The valid sector_size_option is:

                   size=value
                          The sector size is specified with a value in
                          bytes.  The default sector_size is 512 bytes.
                          The minimum value for sector size is 512; the
                          maximum is 32768 (32 KiB). The sector_size
                          must be a power of 2 size and cannot be made
                          larger than the filesystem block size.

       -L label
              Set the filesystem label.  XFS filesystem labels can be at
              most 12 characters long; if label is longer than 12
              characters, mkfs.xfs will not proceed with creating the
              filesystem.  Refer to the mount(8) and xfs_admin(8) manual
              entries for additional information.

       -N     Causes the file system parameters to be printed out
              without really creating the file system.

       -K     Do not attempt to discard blocks at mkfs time.

       -V     Prints the version number and exits.

Configuration File Format         top

       The configuration file uses a basic INI format to specify
       sections and options within a section.  Section and option names
       are case sensitive.  Section names must not contain whitespace.
       Options are name-value pairs, ended by the first whitespace in
       the line.  Option names cannot contain whitespace.  Full line
       comments can be added by starting a line with a # symbol.  If
       values contain whitespace, then it must be quoted.

       The following example configuration file sets the block size to
       4096 bytes, turns on reverse mapping btrees and sets the inode
       size to 2048 bytes.

       # Example mkfs.xfs configuration file

       [block]
       size=4k

       [metadata]
       rmapbt=1

       [inode]
       size=2048

SEE ALSO         top

       xfs(5), mkfs(8), mount(8), xfs_info(8), xfs_admin(8).

BUGS         top

       With a prototype file, it is not possible to specify hard links.

COLOPHON         top

       This page is part of the xfsprogs (utilities for XFS filesystems)
       project.  Information about the project can be found at 
       ⟨http://xfs.org/⟩.  If you have a bug report for this manual page,
       send it to linux-xfs@vger.kernel.org.  This page was obtained
       from the project's upstream Git repository
       ⟨https://git.kernel.org/pub/scm/fs/xfs/xfsprogs-dev.git⟩ on
       2020-12-18.  (At that time, the date of the most recent commit
       that was found in the repository was 2020-12-11.)  If you
       discover any rendering problems in this HTML version of the page,
       or you believe there is a better or more up-to-date source for
       the page, or you have corrections or improvements to the
       information in this COLOPHON (which is not part of the original
       manual page), send a mail to man-pages@man7.org

                                                             mkfs.xfs(8)

Pages that refer to this page: xfs(5)mkfs(8)systemd-makefs@.service(8)xfs_admin(8)xfs_copy(8)xfs_db(8)xfs_fsr(8)xfs_growfs(8)xfs_info(8)xfs_io(8)xfs_logprint(8)xfs_metadump(8)xfs_ncheck(8)xfs_repair(8)xfs_rtcp(8)xfs_scrub(8)