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.TH mkfs.exfat 8
.SH NAME
mkfs.exfat \- create an exFAT filesystem
.SH SYNOPSIS
.B mkfs.exfat
[
.B \-b
.I boundary_alignment
] [
.B \-c
.I cluster_size
] [
.B \-f
] [
.B \-h
] [
.B \-L
.I volume_label
] [
.B \-\-pack\-bitmap
] [
.B \-v
]
.I device
.br
.B mkfs.exfat \-V
.SH DESCRIPTION
.B 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
.BR mkfs (8)
when it is given the
.B \-t exfat
option.
.PP
As an example, to make a filesystem on the first partition on the first
SCSI disk, use:
.IP
.B mkfs.exfat /dev/sda1
.PP
.SH OPTIONS
.TP
.BR \-b ", " \-\-boundary\-align =\fIalignment\fR
Specifies the alignment for the FAT and the start of the cluster heap.
The \fIalignment\fR argument is specified in bytes or may be specified with
\fBm\fR/\fBM\fR suffix for mebibytes or \fBk\fR/\fBK\fR 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 \fIalignment\fR 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.
.\" source: SD Specifications Part 2: File System Specification Version 3.00
.TS
center;
cb1s6cbcb,nnnn.
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
.TE
.TP
.BR \-c ", " \-\-cluster\-size =\fIsize\fR
Specifies the cluster size of the exFAT file system.
The \fIsize\fR argument is specified in bytes or may be specified with
\fBm\fR/\fBM\fR suffix for mebibytes or \fBk\fR/\fBK\fR suffix for kibibytes
and must be a power of two.
.TP
.BR \-f ", " \-\-full\-format
Performs a full format.
This zeros the entire disk device while creating the exFAT filesystem.
.TP
.BR \-h ", " \-\-help
Prints the help and exit.
.TP
.BR \-L ", " \-\-volume\-label =\fIlabel\fR
Specifies the volume label to be associated with the exFAT filesystem.
.TP
.B \-\-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 \[em] where the exFAT bitmap would be placed by default.
Specifying \fB\-\-pack\-bitmap\fR 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.
.TP
.BR \-v ", " \-\-verbose
Prints verbose debugging information while creating the exFAT filesystem.
.TP
.BR \-V ", " \-\-version
Prints the version number and exits.
.SH SEE ALSO
.BR mkfs (8),
.BR mount (8),
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