My commonly used btrfs commands. I enjoy using btrfs as it is compatible with Linux kernel GPL licensing. It’s mainline supported, simple to manage, and it provides me much of the same functionality I get with zfs.

Create a simple mirror

Both data and metadata will be mirrored across these two disks.

mkfs.btrfs --data raid1 --metadata raid1 /dev/my/device/1 /dev/my/device/2

List filesystems

btrfs filesystem show

Attach a new disk to a non-mirrored disk

The goal here is to take a single-device btrfs system and make it into a mirror (raid1). This way we go from having one disk with no redundancy to a pair/set of two disks with redundancy.

btrfs device add /dev/my/new/device /mnt/my/existing/filesystem

This may take a long time to mirror data

btrfs balance start -dconvert=raid1 -mconvert=raid1 /mnt/my/filesystem