mkfs.msdos

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)