mkfs.exfat(8) System Manager's Manual mkfs.exfat(8)
NAME
mkfs.exfat - create an exFAT filesystem
SYNOPSIS
mkfs.exfat [ -b boundary_alignment ] [ -s sector_size ] [ -c clus-
ter_size ] [ -f ] [ -h ] [ -L volume_label ] [ -U volume_guid ] [
--pack-bitmap ] [ -v ] device
mkfs.exfat -V
DESCRIPTION
mkfs.exfat creates an exFAT filesystem by writing on a special file us-
ing the values found in the arguments of the command line. It is in-
voked automatically by mkfs(8) when it is given the -t exfat option.
As an example, to make a filesystem on the first partition on the first
SCSI disk, use:
mkfs.exfat /dev/sda1
OPTIONS
-b, --boundary-align=alignment
Specifies the alignment for the FAT and the start of the cluster
heap. The alignment argument is specified in bytes or may be
specified with m/M suffix for mebibytes or k/K suffix for
kibibytes and should be a power of two. Some media like SD cards
need this for optimal performance and endurance, in which case
alignment should be set to half of the card's native boundary
unit size. If the card's native boundary unit size is not known,
refer to the following table of boundary unit sizes recommended
by the SD Card Association.
Card Capacity Range Cluster Size Boundary Unit
──────────────────────────────────────────────────────
≤8 MiB 8 KiB 8 KiB
>8 MiB ≤64 MiB 16 KiB 16 KiB
>64 MiB ≤256 MiB 16 KiB 32 KiB
>256 MiB ≤1 GiB 16 KiB 64 KiB
>1 GiB ≤2 GiB 32 KiB 64 KiB
>2 GiB ≤32 GiB 32 KiB 4 MiB
>32 GiB ≤128 GiB 128 KiB 16 MiB
>128 GiB ≤512 GiB 256 KiB 32 MiB
>512 GiB ≤2 TiB 512 KiB 64 MiB
The default is always 1 MiB.
-s, --sector-size=size
Specifies the sector size of the exFAT file system. The size ar-
gument is specified in bytes or may be specified with k/K suffix
for kibibytes and must either 512, 1024, 2048 or 4096 bytes. The
default value is the sector size reported by the device, or 512
bytes if the device sector size cannot be determined.
-c, --cluster-size=size
Specifies the cluster size of the exFAT file system. The size
argument is specified in bytes or may be specified with m/M suf-
fix for mebibytes or k/K suffix for kibibytes and must be a power
of two. The default value is described in the following table:
Card Capacity Range Cluster Size
──────────────────────────────────────
≤256 MiB 4 KiB
>256 MiB ≤32 GiB 32 KiB
>32 GiB 128 KiB
-f, --full-format
Performs a full format. This zeros the entire disk device while
creating the exFAT filesystem.
-h, --help
Prints the help and exit.
-L, --volume-label=label
Specifies the volume label to be associated with the exFAT
filesystem.
-U, --volume-guid=guid
Specifies the volume GUID to be associated with the exFAT
filesystem. It can be given in the standard, hypenized UUID for-
mat like aaaabbbb-cccc-dddd-eeee-ffff00001111. Note: The volume
GUID cannot be used to set the the 8-letter ID reported by blkid
or used as the filesystem UUID in /etc/fstab.
--pack-bitmap
Attempts to relocate the exFAT allocation bitmap so that it ends
at the alignment boundary immediately following the FAT rather
than beginning at that boundary. This strictly violates the SD
card specification but may improve performance and endurance on
SD cards and other flash media not designed for use with exFAT by
allowing file-system metadata updates to touch fewer flash allo-
cation units. Furthermore, many SD cards and other flash devices
specially optimize the allocation unit where the FAT resides so
as to support tiny writes with reduced write amplification but
expect only larger writes in subsequent allocation units — where
the exFAT bitmap would be placed by default. Specifying
--pack-bitmap attempts to avoid the potential problems associated
with issuing many small writes to the bitmap by making it share
an allocation unit with the FAT. If there is insufficient space
for the bitmap there, then this option will have no effect, and
the bitmap will be aligned at the boundary as by default.
-q, --quiet
Prints only error messages while creating the exFAT filesystem.
-v, --verbose
Prints verbose debugging information while creating the exFAT
filesystem.
-V, --version
Prints the version number and exits.
SEE ALSO
mkfs(8), mount(8),
mkfs.exfat(8)
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