MKFS.BTRFS(8) System Manager's Manual MKFS.BTRFS(8)
mkfs.btrfs - create a btrfs filesystem
mkfs.btrfs [ -A alloc-start ] [ -b byte-count ] [ -d data-profile ] [ -f ] [ -n nodesize ] [ -l leafsize ] [ -L label ] [ -m metadata pro-
file ] [ -M mixed data+metadata ] [ -s sectorsize ] [ -r rootdir ] [ -K ] [ -O feature1,feature2,... ] [ -h ] [ -V ]
device [ device ... ]
mkfs.btrfs is used to create a btrfs filesystem (usually in a disk partition, or an array of disk partitions). device is the special file
corresponding to the device (e.g /dev/sdXX ). If multiple devices are specified, btrfs is created spanning across the specified
-A, --alloc-start offset
Specify the offset from the start of the device to start the btrfs filesystem. The default value is zero, or the start of the
-b, --byte-count size
Specify the size of the resultant filesystem. If this option is not used, mkfs.btrfs uses all the available storage for the filesys-
-d, --data type
Specify how the data must be spanned across the devices specified. Valid values are raid0, raid1, raid5, raid6, raid10 or single.
Force overwrite when an existing filesystem is detected on the device. By default, mkfs.btrfs will not write to the device if it
suspects that there is a filesystem or partition table on the device already.
-n, --nodesize size
-l, --leafsize size Specify the nodesize, the tree block size in which btrfs stores data. The default value is the page size. Must
be a multiple of the sectorsize, but not larger than 65536. Leafsize always equals nodesize and the options are aliases.
-L, --label name
Specify a label for the filesystem.
-m, --metadata profile
Specify how metadata must be spanned across the devices specified. Valid values are raid0, raid1, raid5, raid6, raid10, single or
dup. Single device will have dup set by default except in the case of SSDs which will default to single. This is because SSDs can
remap blocks internally so duplicate blocks could end up in the same erase block which negates the benefits of doing metadata dupli-
Mix data and metadata chunks together for more efficient space utilization. This feature incurs a performance penalty in larger
filesystems. It is recommended for use with filesystems of 1 GiB or smaller.
-s, --sectorsize size
Specify the sectorsize, the minimum data block allocation unit. The default value is the page size. If the sectorsize differs from
the page size, the created filesystem may not be mountable by current kernel. Therefore it is not recommended to use this option
unless you are going to mount it on a system with the appropriate page size.
-r, --rootdir rootdir
Specify a directory to copy into the newly created fs.
Do not perform whole device TRIM operation by default.
-O, --features feature1,feature2,...
A list of filesystem features turned on at mkfs time. Not all features are supported by old kernels.
To see all run
mkfs.btrfs -O list-all
Print the mkfs.btrfs version and exit.
As default the unit is the byte, however it is possible to append a suffix to the arguments like k for KBytes, m for MBytes...
mkfs.btrfs is part of btrfs-progs. Btrfs is currently under heavy development, and not suitable for any uses other than benchmarking and
review. Please refer to the btrfs wiki http://btrfs.wiki.kernel.org for further details.