https://www.howtoforge.com/a-beginners-guide-to-btrfs
https://www.howtoforge.com/how-to-convert-an-ext3-ext4-root-file-system-to-btrfs-on-ubuntu-12.10
http://www.oracle.com/technetwork/articles/servers-storage-admin/advanced-btrfs-1734952.html
Create BTRFS filesystem on multiple block devices:
mkfs.btrfs /dev/loop0 /dev/loop1
btrfs filesystem show /dev/loop0
Label: none uuid: e9a456cd-57d7-4355-a20a-77243d66722e
Total devices 2 FS bytes used 28.00KiB
devid 1 size 200.00MiB used 12.00MiB path /dev/loop0
devid 2 size 200.00MiB used 0.00B path /dev/loop1
As you can see, every block belongs to FS can be used. Also for mount:
mount /dev/loop0 /BTRFS
or
mount /dev/loop1 /BTRFS
Current state: Do not create SWAP files on BTRFS!
Swap support was restored with Kernel 4.21
Add new block device (extend size)
btrfs device add /dev/loop2 /BTRFS
Remove device:
btrfs device delete /dev/loop0 /BTRFS
!!! It is possible to remove any device if there is free space to which data can be moved during removal.
Start foreground, readonly scrub, print statistics at end:
btrfs scrub start -B -d -r / scrub device /dev/sda3 (id 1) done scrub started at Mon Mar 6 07:02:56 2017 and finished after 00:04:06 total bytes scrubbed: 18.50GiB with 0 errors scrub device /dev/sdc5 (id 2) done scrub started at Mon Mar 6 07:02:56 2017 and finished after 00:06:52 total bytes scrubbed: 18.47GiB with 0 errors
Get currently running scrub status:
btrfs scrub status /
apt-get install btrfs-tools
GRUB 2.02 doesn't support ZSTD compression.
Solution is to exlude /boot from ZSTD compression (below) or install more recent Grub (from Debian Bullseye)
sudo btrfs filesystem defragment -v -r -czlib /boot sudo btrfs property set /boot compression zlib # disable compression for newly created files chattr -Rc /boot
31 #define ENOSPC 28 /* No space left on device */
# btrfs fi show /mount Label: none uuid: 5db83d5e-4f38-40b0-ac5d-dadd9cd1d23f Total devices 1 FS bytes used 22.18GiB devid 1 size 30.00GiB used 27.58GiB path /dev/mapper/vg_spox-lv_home # btrfs fi usage /mount Overall: Device size: 30.00GiB Device allocated: 27.58GiB Device unallocated: 2.42GiB Device missing: 0.00B Used: 22.52GiB Free (estimated): 5.58GiB (min: 4.37GiB) Data ratio: 1.00 Metadata ratio: 1.99 Global reserve: 512.00MiB (used: 0.00B) Data,single: Size:25.01GiB, Used:21.84GiB /dev/mapper/... 25.01GiB Metadata,single: Size:8.00MiB, Used:0.00B /dev/mapper/... 8.00MiB Metadata,DUP: Size:1.25GiB, Used:348.23MiB /dev/mapper/... 2.50GiB System,single: Size:4.00MiB, Used:0.00B /dev/mapper/... 4.00MiB System,DUP: Size:32.00MiB, Used:16.00KiB /dev/mapper/... 64.00MiB Unallocated: /dev/mapper/... 2.42GiB
https://bbs.archlinux.org/viewtopic.php?id=200817 http://www.mail-archive.com/linux-btrfs@vger.kernel.org/msg60637.html