Should I use a btrfs pool?

I’m currently using a 2TB drive with btrfs where I’m running out of space.

I have a different 1TB drive that I’m currently not using.

I see two options:

  • Format the 1TB drive and mount it somewhere so that I can store things on it. It’s probably the easiest solution, but I don’t like it because I wouldn’t use the available space to it’s full potential.
  • Add the 1TB drive to a btrfs pool and have a combined 3TB drive. I like this option, but I’m not sure if this is actually a good idea. I’ve read things about issues with some forms of configuration, and I’m not entirely sure if they apply to what I want to do.

You can add the device to your existing btrfs filesystem which will expand it’s size.

However, you should only do this if the performance characteristics of the two drives are similar.

They have the same read/write speed, but are just of different size. So I’m fine then? Right?

I would not do that. Putting two devices in one RAID0 actually doubles the failure probability. If either drive A or B fails, the whole pool is gone.

I would rather leave them as separate drives and do a “manual load balancing” by moving folders / subvolumes / mountpoints from one drive to the other. With such a setup both drives are independent from each other and if drive A fails you still have drive B.