mkfs.xfs

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



NAME
       mkfs.xfs - construct an XFS filesystem

SYNOPSIS
       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
       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
       -b block_size_options
              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
              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:

                   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.

                   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
              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 set, all inodes created by mkfs.xfs will be
                          created with the realtime flag set.  Directories
                          will pass on this flag to newly created regular
                          files and directories.

                   projinherit=value
                          All inodes created by mkfs.xfs will be assigned this
                          project quota id.  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 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 set, all inodes created by mkfs.xfs will be
                          created with the DAX flag set.  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
              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
              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
              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
              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
              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.

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)