BTRFS JBOD setup

Btrfs.md

Simple commands to setup a BTRFS filesystem across multiple disks as a JBOD implementation.

# Create a filesystem across the drives (metadata mirrored, linear data allocation)
sudo mkfs.btrfs -f -L MEDIA -d single -m raid1 /dev/mapper/data-*

To show all the filesystems

sudo btrfs filesystem show

To check filesystem usage

sudo btrfs filesystem df /mnt/media

In order to then add a disk to this filesystem later

sudo btrfs device add /dev/sdb /mnt/media
btrfs filesystem balance /mnt/media

We can also convert another btrfs filesystem data allocation (e.g. RAID1) to single as part of the balance process.

sudo btrfs balance start -dconvert=single,soft /mnt/media

As far as I’m aware. Alternatively a better approach is probably to use MergerFS to combine the disks and then, optionally, use SnapRAID. Depends on the type of media being stored but that’s the approach I’ve got for:

• LUKS encrypt each disk individually
• Mount at boot time
• MergerFS combines into a virtual filesystem

Is this still a viable option? I would like to do this for my home media NAS.

btrfs doesn't have really jbod/linear option afaik. When you do multivolume btrfs with data profile single, it works very similar as you would be using it as raid-0. Distributing data evenly to all available drives, 1GB chunks. So if one drive fails, you end up losing most of the data what is greater than 1GB.