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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 hand‐
           ful 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 GEM‐
           DOS 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 filesys‐
           tem 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 actu‐
           ally 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  oth‐
       ers.  The current maintainer is Andreas Bombe ⟨aeb@debian.org⟩.


1		MKFS.FAT(8) System Manager's Manual MKFS.FAT(8)
2
3		NAME
4		mkfs.fat - create an MS-DOS filesystem under Linux
5
6		SYNOPSIS
7		mkfs.fat [OPTIONS] DEVICE [BLOCK-COUNT]
8
9		DESCRIPTION
10		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
11		the device (e.g. /dev/sdXX). BLOCK-COUNT is the number of blocks on the device. If omitted, mkfs.fat automatically determines the filesystem
12		size.
13
14		OPTIONS
15		-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
16		the partition is properly aligned, so will all the data structures in the filesystem. This option disables alignment; this may provide a hand‐
17		ful of additional clusters of storage at the expense of a significant performance degradation on RAIDs, flash media or large-sector hard disks.
18
19		-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
20		are some differences when using Atari format: If not directed otherwise by the user, mkfs.fat will always use 2 sectors per cluster, since GEM‐
21		DOS doesn't like other values very much. It will also obey the maximum number of sectors GEMDOS can handle. Larger filesystems are managed by
22		raising the logical sector size. Under Atari format, an Atari-compatible serial number for the filesystem is generated, and a 12 bit FAT is
23		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
24		with the -F option. Some PC-specific boot sector fields aren't written, and a boot message (option -m) is ignored.
25
26		-b SECTOR-OF-BACKUP
27		Selects the location of the backup boot sector for FAT32. Default depends on number of reserved sectors, but usually is sector 6. The backup
28		must be within the range of reserved sectors.
29
30		-c Check the device for bad blocks before creating the filesystem.
31
32		-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 filesys‐
33		tem 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-
34		COUNT must be given, because otherwise the intended size of the filesystem wouldn't be known. The file created is a sparse file, which actu‐
35		ally 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
36		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
37		device.
38
39		-D DRIVE-NUMBER
40		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
41		partitions to be used for floppy emulation.
42
43		-f NUMBER-OF-FATS
44		Specify the number of file allocation tables in the filesystem. The default is 2.
45
46		-F FAT-SIZE
47		Specifies the type of file allocation tables used (12, 16 or 32 bit). If nothing is specified, mkfs.fat will automatically select between 12,
48		16 and 32 bit, whatever fits better for the filesystem size.
49
50		-h NUMBER-OF-HIDDEN-SECTORS
51		Select the number of hidden sectors in the volume. Apparently some digital cameras get indigestion if you feed them a CF card without such
52		hidden sectors, this option allows you to satisfy them.
53
54		-i VOLUME-ID
55		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
56		which depends on the filesystem creation time.
57
58		-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.
59		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
60		disks. The filesystem can go directly to the whole disk. Under other OSes this is known as the 'superfloppy' format. This switch will force
61		mkfs.fat to work properly.
62
63		-l FILENAME
64		Read the bad blocks list from FILENAME.
65
66		-m MESSAGE-FILE
67		Sets the message the user receives on attempts to boot this filesystem without having properly installed an operating system. The message file
68		must not exceed 418 bytes once line feeds have been converted to carriage return-line feed combinations, and tabs have been expanded. If the
69		filename is a hyphen (-), the text is taken from standard input.
70
71		-M FAT-MEDIA-TYPE
72		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
73		for floppies or partitions to be used for floppy emulation.
74
75		-n VOLUME-NAME
76		Sets the volume name (label) of the filesystem. The volume name can be up to 11 characters long. The default is no label.
77
78		-r ROOT-DIR-ENTRIES
79		Select the number of entries available in the root directory. The default is 112 or 224 for floppies and 512 for hard disks.
80
81		-R NUMBER-OF-RESERVED-SECTORS
82		Select the number of reserved sectors. With FAT32 format at least 2 reserved sectors are needed, the default is 32. Otherwise the default is
83		1 (only the boot sector).
84
85		-s SECTORS-PER-CLUSTER
86		Specify the number of disk sectors per cluster. Must be a power of 2, i.e. 1, 2, 4, 8, ... 128.
87
88		-S LOGICAL-SECTOR-SIZE
89		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,
90		16384, or 32768. Values larger than 4096 are not conforming to the FAT file system specification and may not work everywhere.
91
92		-v Verbose execution.
93
94		--invariant
95		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
96		device create identical results with this option. Its main purpose is testing mkfs.fat.
97
98		--help
99		Display option summary and exit.
100
101		BUGS
102		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
103		lot already. mkfs.fat simply will not support it ;)
104
105		SEE ALSO
106		fatlabel(8)
107		fsck.fat(8)
108
109		HOMEPAGE
110		The home for the dosfstools project is its GitHub project page ⟨https://github.com/dosfstools/dosfstools⟩.
111
112		AUTHORS
113		dosfstools were written by Werner Almesberger ⟨werner.almesberger@lrc.di.epfl.ch⟩, Roman Hodek ⟨Roman.Hodek@informatik.uni-erlangen.de⟩, and oth‐
114		ers. The current maintainer is Andreas Bombe ⟨aeb@debian.org⟩.
115