# pacman -S btrfs-progs
UUID=2dc70a6e-b4cf-4d94-b326-0ba9f886cf49 /mnt/tmp btrfs defaults,noatime,compress-force=zstd,space_cache=v2,subvol=@ 0 0
Options:
defaults -> Use whatever defaults
noatime -> Reading access to a file is not recorded
compress-force -> Send all files through the compression algorithm
space_cache -> Increases performance by mapping unallocated blocks
subvol -> Subvolume to mountShow storage allocated, used and free
# btrfs fi usage (mountpoint)
allocated: space used
unallocated: actual free space
Used: amount of data stored
Free: free storage based on "Used"Start rebalance of datachunks filled less than 70%
# btrfs balance start --b -dusage=70 -musage=70 (mountpoint)
Check status of rebalance
# btrfs balance status -v (mountpoint)
Disable copy on write for folders (Only works on new files)
$ chattr +C (path)
Error counts for a given mountpoint
# btrfs dev stat (mountpoint)
zlib: Slow, but strong compression, level 1-9
lzo : Fastest, weak compression
zstd: [Recommended] Medium, newer compression standard than the others, only works on newer kernels, level 1-15Enable compression for existing files
# btrfs filesystem defragment -r -v -c(alg) (path)
It is impossible to specify the level of compression wanted.
Add compress=(alg) to /etc/fstab
To specify a level of compression (zlib and zstd) use compress=(alg):(level) in fstab.
For zstd compression it is recommended to use compress-force=zstd:(level)
List
# btrfs subv list (path)
Create
# btrfs subv create (path)
Mount a subvolume
# mount -o subvol=@(subvolname) /dev/sdXX /(mountpoint)
TODO
An array can be mounted by specifying one of its members.
# mount /dev/sdXX /mnt
All members of an array have the same UUID, which can be mounted through fstab.
On filesystem creation
# mkfs.btrfs -m raid1 -d raid1 /dev/sdXX /dev/sdYY
On filesystem creation
It is recommended not to use raid5/6 for metadata yet
# mkfs.btrfs -m raid1 -d raid5 /dev/sdXX /dev/sdYY /dev/sdZZ
On filesystem creation
# mkfs.btrfs -m raid10 -d raid10 /dev/sdXX /dev/sdYY /dev/sdZZ /dev/sdQQ
First, the files have to be collected on one device.
DUP on system and metadata should only be used on HDDs. Use single on SSDs
# btrfs balance start -f -sconvert=dup,devid=(id) -mconvert=dup,devid=(id) -dconvert=single,devid=(id) /(mountpoint)
Now unused devices can be removed
# btrfs device delete /dev/sdYY /(mountpoint)
Show arrays that are available
btrfs fi show
From my testing the log has to be dropped before btrfs will mount the incomplete array
btrfs rescue zero-log /dev/sdXX
Mount with these options to be able to fix it
mount -o rw,degraded /(mountpoint)
The ID has to be replaced with the ID of the missing device!
btrfs replace start -B (id) /dev/sdYY /(mountpoint)
Query the status of the repace
btrfs replace status /(mountpoint)
Balance the filesystem at the end
btrfs balance /(mountpoint)
btrfs-transaction and btrfs-cleaner will run on a single cpu core, maxing it out with 100% load.
TODO: Check what enabled quotas in the first place. A likely candidate is snapper
The issue is apparently caused by using quotas in btrfs.
Check if quotas are enabled:
# btrfs qgroup show (path)
Disable quotas:
# btrfs quota disable (path)