According to this post it is possible to have multiple pools within Unassigned Devices:

 

I could wipe old filesystems on two old drives, format them with BTRFS, did mount and rename the first drive. But converting to RAID1 did not work. Whats wrong with this?

 

root@Tower:~# btrfs dev add -f /dev/sdi1 /mnt/disks/UD01
root@Tower:~# btrfs balance start -dconvert=raid1 -mconvert=raid1 /mnt/disks/UD01
-bash: btrfs: command not found
root@Tower:~# whereis btrfs
btrfs: /sbin/btrfs
root@Tower:~# /sbin/btrfs balance start -dconvert=raid1 -mconvert=raid1 /mnt/disks/UD01
-bash: /sbin/btrfs: No such file or directory

Thanks in advynce.

 

Edited November 28, 20187 yr by hawihoney

I don't understand why you're getting a "No such file or directory" error from bash, as though the /sbin/btrfs file is missing. What do you get if you just type

btrfs

at the prompt? It should give you a brief summary of how to use the command. What does

ls -l /sbin/btrfs

produce?

Uah, found it. I had to retype every character and blank. I did copy&paste that command out of the post mentioned in my OP. Seems that there were alien character sin there.

 

Thanks a lot.

 

Ok. No problem. So, presumably you typed the first line (btrfs dev add ...) because that worked ok. Come to think of it, I've had that before when copy/pasting into the command line. BTW, what you're trying to do really does work. I have four 2 TB disks in RAID 10 mounted like that. You have to do everything from the command line but at least you can use the Unassigned Devices plugin to mount and unmount the volume and trigger scripts as it does so. Maybe one day it will be integrated into the GUI but for the time being this works fine.

May I ask you a question? The RAID1 pool is working currently. Do I need to re-issue these commands (BTRFS add, BTRFS balance start) after a server reboot? If yes, what's the best place to let these commands run automatically after a server reboot (Unassigned Devices script?)

 

BTW, performance of that BTRFS RAID1 pool seems to be degraded by 10% compared with a single XFS formatted drive.

 

2 hours ago, hawihoney said:

Do I need to re-issue these commands (BTRFS add, BTRFS balance start) after a server reboot?

No, you just need to mount one of the devices, use the first one to get an accurate used/free space on the GUI, you can also set it to auto mount with UD.

Thanks a lot.