mkfs.vfat

MKFS.FAT(8)                  System Manager's Manual                 MKFS.FAT(8)



NAME
       mkfs.fat - create an MS-DOS filesystem under Linux

SYNOPSIS
       mkfs.fat [OPTIONS] DEVICE [BLOCK-COUNT]

DESCRIPTION
       mkfs.fat is used to create an MS-DOS filesystem under Linux on a device
       (usually a disk partition).  DEVICE is the special file corresponding to
       the device (e.g. /dev/sdXX).  BLOCK-COUNT is the number of blocks on the
       device.  If omitted, mkfs.fat automatically determines the filesystem
       size.

OPTIONS
       -a  Normally, for any filesystem except very small ones, mkfs.fat will
           align all the data structures to cluster size, to make sure that as
           long as the partition is properly aligned, so will all the data
           structures in the filesystem.  This option disables alignment; this
           may provide a handful of additional clusters of storage at the
           expense of a significant performance degradation on RAIDs, flash
           media or large-sector hard disks.

        -A Use Atari variation of the MS-DOS filesystem.  This is default if
           mkfs.fat is run on an Atari, then this option turns off Atari format.
           There are some differences when using Atari format: If not directed
           otherwise by the user, mkfs.fat will always use 2 sectors per
           cluster, since GEMDOS doesn't like other values very much.  It will
           also obey the maximum number of sectors GEMDOS can handle.  Larger
           filesystems are managed by raising the logical sector size.  Under
           Atari format, an Atari-compatible serial number for the filesystem is
           generated, and a 12 bit FAT is used only for filesystems that have
           one of the usual floppy sizes (720k, 1.2M, 1.44M, 2.88M), a 16 bit
           FAT otherwise.  This can be overridden with the -F option.  Some PC-
           specific boot sector fields aren't written, and a boot message
           (option -m) is ignored.

       -b SECTOR-OF-BACKUP
           Selects the location of the backup boot sector for FAT32.  Default
           depends on number of reserved sectors, but usually is sector 6.  The
           backup must be within the range of reserved sectors.

       -c  Check the device for bad blocks before creating the filesystem.

       -C  Create the file given as DEVICE on the command line, and write the
           to-be-created filesystem to it.  This can be used to create the new
           filesystem in a file instead of on a real device, and to avoid using
           dd in advance to create a file of appropriate size.  With this
           option, the BLOCK-COUNT must be given, because otherwise the intended
           size of the filesystem wouldn't be known.  The file created is a
           sparse file, which actually only contains the meta-data areas (boot
           sector, FATs, and root directory).  The data portions won't be stored
           on the disk, but the file nevertheless will have the correct size.
           The resulting file can be copied later to a floppy disk or other
           device, or mounted through a loop device.

       -D DRIVE-NUMBER
           Specify the BIOS drive number to be stored in the FAT boot sector.
           This value is usually 0x80 for hard disks and 0x00 for floppy devices
           or partitions to be used for floppy emulation.

       -f NUMBER-OF-FATS
           Specify the number of file allocation tables in the filesystem.  The
           default is 2.

       -F FAT-SIZE
           Specifies the type of file allocation tables used (12, 16 or 32 bit).
           If nothing is specified, mkfs.fat will automatically select between
           12, 16 and 32 bit, whatever fits better for the filesystem size.

       -h NUMBER-OF-HIDDEN-SECTORS
           Select the number of hidden sectors in the volume.  Apparently some
           digital cameras get indigestion if you feed them a CF card without
           such hidden sectors, this option allows you to satisfy them.

       -i VOLUME-ID
           Sets the volume ID of the newly created filesystem; VOLUME-ID is a
           32-bit hexadecimal number (for example, 2e24ec82).  The default is a
           number which depends on the filesystem creation time.

       -I  It is typical for fixed disk devices to be partitioned so, by
           default, you are not permitted to create a filesystem across the
           entire device.  mkfs.fat will complain and tell you that it refuses
           to work.  This is different when using MO disks.  One doesn't always
           need partitions on MO disks.  The filesystem can go directly to the
           whole disk.  Under other OSes this is known as the 'superfloppy'
           format.  This switch will force mkfs.fat to work properly.

       -l FILENAME
           Read the bad blocks list from FILENAME.

       -m MESSAGE-FILE
           Sets the message the user receives on attempts to boot this
           filesystem without having properly installed an operating system.
           The message file must not exceed 418 bytes once line feeds have been
           converted to carriage return-line feed combinations, and tabs have
           been expanded.  If the filename is a hyphen (-), the text is taken
           from standard input.

       -M FAT-MEDIA-TYPE
           Specify the media type to be stored in the FAT boot sector.  This
           value is usually 0xF8 for hard disks and is 0xF0 or a value from 0xF9
           to 0xFF for floppies or partitions to be used for floppy emulation.

       -n VOLUME-NAME
           Sets the volume name (label) of the filesystem.  The volume name can
           be up to 11 characters long.  The default is no label.

       -r ROOT-DIR-ENTRIES
           Select the number of entries available in the root directory.  The
           default is 112 or 224 for floppies and 512 for hard disks.

       -R NUMBER-OF-RESERVED-SECTORS
           Select the number of reserved sectors.  With FAT32 format at least 2
           reserved sectors are needed, the default is 32.  Otherwise the
           default is 1 (only the boot sector).

       -s SECTORS-PER-CLUSTER
           Specify the number of disk sectors per cluster.  Must be a power of
           2, i.e. 1, 2, 4, 8, ... 128.

       -S LOGICAL-SECTOR-SIZE
           Specify the number of bytes per logical sector.  Must be a power of 2
           and greater than or equal to 512, i.e. 512, 1024, 2048, 4096, 8192,
           16384, or 32768.  Values larger than 4096 are not conforming to the
           FAT file system specification and may not work everywhere.

       -v  Verbose execution.

       --invariant
           Use constants for normally randomly generated or time based data such
           as volume ID and creation time.  Multiple runs of mkfs.fat on the
           same device create identical results with this option.  Its main
           purpose is testing mkfs.fat.

       --help
           Display option summary and exit.

BUGS
       mkfs.fat can not create boot-able filesystems.  This isn't as easy as you
       might think at first glance for various reasons and has been discussed a
       lot already.  mkfs.fat simply will not support it ;)

SEE ALSO
       fatlabel(8)
       fsck.fat(8)

HOMEPAGE
       The home for the dosfstools project is its GitHub project page
       ⟨https://github.com/dosfstools/dosfstools⟩.

AUTHORS
       dosfstools were written by Werner Almesberger ⟨werner.almesberger@
       lrc.di.epfl.ch⟩, Roman Hodek ⟨Roman.Hodek@informatik.uni-erlangen.de⟩,
       and others.  The current maintainer is Andreas Bombe ⟨aeb@debian.org⟩.



dosfstools 4.1                     2016-01-25                        MKFS.FAT(8)