6.3. Resizing a btrfs File System It is not possible to resize a btrfs file system but it is possible to resize each of the devices it uses. If there is only one device in use then this works the same as resizing the file system. If there are multiple devices in use then they must be manually resized to achieve the desired result. Note The unit size is not case specific; it accepts both G or g for GiB. The command does not accept t for terabytes or p for petabytes. It only accepts k , m , and g . Enlarging a btrfs File System To enlarge the file system on a single device, use the command: For example: To enlarge a multi-device file system, the device to be enlarged must be specified. First, show all devices that have a btrfs file system at a specified mount point: For example: Then, after identifying the devid of the device to be enlarged, use the following command: For example: Note The amount can also be max instead of a specified amount. This will use all remaining free space on the device. Shrinking a btrfs File System To shrink the file system on a single device, use the command: For example: To shrink a multi-device file system, the device to be shrunk must be specified. First, show all devices that have a btrfs file system at a specified mount point: For example: Then, after identifying the devid of the device to be shrunk, use the following command: For example: Set the File System Size To set the file system to a specific size on a single device, use the command: For example: To set the file system size of a multi-device file system, the device to be changed must be specified. First, show all devices that have a btrfs file system at the specified mount point: For example: Then, after identifying the devid of the device to be changed, use the following command: For example:

Commands:
btrfs filesystem resize amount / mount-point
btrfs filesystem resize +200M /btrfssingle Resize '/btrfssingle' of '+200M'
btrfs filesystem show /mount-point
btrfs filesystem show /btrfstest Label: none uuid: 755b41b7-7a20-4a24-abb3-45fdbed1ab39 Total devices 4 FS bytes used 192.00KiB devid 1 size 1.00GiB used 224.75MiB path /dev/vdc devid 2 size 524.00MiB used 204.75MiB path /dev/vdd devid 3 size 1.00GiB used 8.00MiB path /dev/vde devid 4 size 1.00GiB used 8.00MiB path /dev/vdf Btrfs v3.16.2
btrfs filesystem resize devid : amount /mount-point
btrfs filesystem resize 2:+200M /btrfstest Resize '/btrfstest/' of '2:+200M'
btrfs filesystem resize amount / mount-point
btrfs filesystem resize -200M /btrfssingle Resize '/btrfssingle' of '-200M'
btrfs filesystem show /mount-point
btrfs filesystem show /btrfstest Label: none uuid: 755b41b7-7a20-4a24-abb3-45fdbed1ab39 Total devices 4 FS bytes used 192.00KiB devid 1 size 1.00GiB used 224.75MiB path /dev/vdc devid 2 size 524.00MiB used 204.75MiB path /dev/vdd devid 3 size 1.00GiB used 8.00MiB path /dev/vde devid 4 size 1.00GiB used 8.00MiB path /dev/vdf Btrfs v3.16.2
btrfs filesystem resize devid : amount /mount-point
btrfs filesystem resize 2:-200M /btrfstest Resize '/btrfstest' of '2:-200M'
btrfs filesystem resize amount / mount-point
btrfs filesystem resize 700M /btrfssingle Resize '/btrfssingle' of '700M'
btrfs filesystem show / mount-point
btrfs filesystem show /btrfstest Label: none uuid: 755b41b7-7a20-4a24-abb3-45fdbed1ab39 Total devices 4 FS bytes used 192.00KiB devid 1 size 1.00GiB used 224.75MiB path /dev/vdc devid 2 size 724.00MiB used 204.75MiB path /dev/vdd devid 3 size 1.00GiB used 8.00MiB path /dev/vde devid 4 size 1.00GiB used 8.00MiB path /dev/vdf Btrfs v3.16.2
btrfs filesystem resize devid : amount /mount-point
btrfs filesystem resize 2:300M /btrfstest Resize '/btrfstest' of '2:300M'