Section 8 · System administration

mkfs.exfat.8

Package: exfatprogs

mkfs.exfat

NAME
SYNOPSIS
DESCRIPTION
OPTIONS
SEE ALSO

NAME

mkfs.exfat − create an exFAT filesystem

SYNOPSIS

mkfs.exfat [ −b boundary_alignment ] [ −c cluster_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 using the values found in the arguments of the command line. It is invoked 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.

−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 suffix 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.

−−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 allocation 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.