btrfs

Btrfs Management

Command	Description
`mkfs.btrfs /dev/sdX`	Create a new Btrfs filesystem
`mount /dev/sdX /mnt`	Mount Btrfs filesystem
`umount /mnt`	Unmount filesystem
`btrfs filesystem show`	Show Btrfs filesystems
`btrfs filesystem df /mnt`	Show space usage
`btrfs filesystem usage /mnt`	Detailed space usage

Command	Description
`mkfs.btrfs -d raid1 -m raid1 /dev/sdb /dev/sdc`	Create RAID1 (mirror)
`mkfs.btrfs -d raid0 -m raid0 /dev/sdb /dev/sdc`	Create RAID0 (striping)
`mkfs.btrfs -d raid10 -m raid10 /dev/sdb /dev/sdc /dev/sdd /dev/sde`	Create RAID10
`btrfs device add /dev/sdd /mnt`	Add device to filesystem
`btrfs device remove /dev/sdc /mnt`	Remove device from filesystem
`btrfs balance start -dconvert=raid1 -mconvert=raid1 /mnt`	Convert existing FS to RAID1
`btrfs balance start /mnt`	Rebalance data across devices
`btrfs device stats /mnt`	Show device stats

Command	Description
`btrfs subvolume create /mnt/data`	Create subvolume
`btrfs subvolume list /mnt`	List subvolumes
`btrfs subvolume delete /mnt/data`	Delete subvolume
`btrfs subvolume snapshot /mnt/data /mnt/data-snap`	Snapshot a subvolume
`btrfs subvolume snapshot -r /mnt/data /mnt/data-ro`	Create readonly snapshot

Command	Description
`btrfs subvolume snapshot /mnt/data /mnt/data-snap`	Create snapshot
`btrfs subvolume delete /mnt/data-snap`	Delete snapshot
`btrfs send /mnt/data-snap	btrfs receive /mnt/backup`

Command	Description
`btrfs scrub start /mnt`	Start scrub on mounted FS
`btrfs scrub status /mnt`	Show scrub status
`btrfs scrub cancel /mnt`	Cancel scrub
`btrfs check /dev/sdX`	Check filesystem (offline)
`btrfs rescue super-recover /dev/sdX`	Try to recover superblock

Command	Description
`btrfs filesystem resize +10G /mnt`	Grow FS by 10G
`btrfs filesystem resize -5G /mnt`	Shrink FS by 5G
`btrfs filesystem resize max /mnt`	Use full device size

mkfs.btrfs -d raid1 -m raid1 /dev/sdb /dev/sdc
mount /dev/sdb /mnt

btrfs device add /dev/sdd /mnt
btrfs balance start -dconvert=raid1 -mconvert=raid1 /mnt

btrfs subvolume snapshot /mnt/data /mnt/data-snap
btrfs subvolume delete /mnt/data
btrfs subvolume snapshot /mnt/data-snap /mnt/data

Command	Description
`btrfs qgroup show -re /mnt/btrfs_volume`	Shows limits of the volume
`btrfs qgroup limit 3T /mnt/btrfs_subvolume`	Sets limit for this subvolume

Option	Description
`compress=zstd`	Enable compression (recommended: zstd)
`compress=lzo`	LZO compression (fast, less efficient)
`compress-force=zstd`	Force compression for all data
`autodefrag`	Auto defragmentation on write
`ssd`	Optimize for SSD (usually auto-detected)
`ssd_spread`	Alternative SSD write strategy
`space_cache=v2`	Faster mount via allocation cache
`discard=async`	Asynchronous TRIM for SSD
`noatime`	Disable access time updates
`nodatacow`	Disable Copy-on-Write
`subvol=`	Mount specific subvolume
`subvolid=`	Mount by subvolume ID

Example fstab entry:

/dev/sdb /mnt btrfs defaults,compress=zstd,autodefrag,ssd,discard=async 0 0