Btrfs

• list available devices

btrfs device scan

• list available filesystems

btrfs filesystem show

• create volume

mkfs.btrfs /dev/sdX

• stripe across devices (mirror metadata + stripe data)

mkfs.btrfs /dev/sda /dev/sdb /dev/sdc

• stripe across devices (stripe metadata + stripe data)

mkfs.btrfs -m raid0 /dev/sda /dev/sdb /dev/sdc

• mirror across devices (mirror metadata + mirror data)

mkfs.btrfs -m raid10 -d raid10 /dev/sda /dev/sdb /dev/sdc

• create subvolume

btrfs subvolume create /mnt/nonsense

where /mnt is the mountpoint of the btrfs volume

• list subvolumes

btrfs subvolume list /mnt 

• create snapshot

mkdir /mnt/snapshots
btrfs subvolume snapshot /mnt/nonsense /mnt/snapshots/vrijdag

• add a new device

btrfs device add /dev/sda8 /mnt

• remove a device

btrfs delete /dev/sdb /mnt

• free space:

btrfs fi df /

• show snapshots

snapper list

• delete all snapshots

for i in {1..20000}; do snapper delete $i; done

2015:

• balance om ruimte vrij te maken:

btrfs balance start /tmp/bla

als geen ruimte vrij:

btrfs balance start -musage=50 -dusage=50 /tmp/bla

btrfs fi show /tmp/bla
btrfs fi df /tmp/bla

Onderhoud:

btrfs scrub is used to scrub a btrfs filesystem, which will read all data and metadata blocks from all devices and verify checksums. Automatically repair corrupted blocks if there’s a correct copy available.

btrfs scrub start -B /tmp/bla
fstrim /tmp/bla

for conventiaonal HD's:

btrfs filesystem defragment /tmp/mnt/bla

recursief een directory:

btrfs filesystem defragment -r /tmp/mnt/bla