Multiple btrfs volumes with different RAID levels on the same devices

btrfs

I have two disks – one xGB and one (2x)GB. I would like to have one mountpoint from these disks under raid0 and one under raid1, spread over the total available space. Is that possible with btrfs without creating two fixed-size primary partitions on each disk?

What I would like is this layout:

disk1 |< -- /home (raid1) -- >< -- /backups (raid0) -- >|
disk2 |< -- /home (raid1) -- >< -- /backups (raid0) ----------------------- >|

Each mount point should expand as necessary.

Best Answer

No, that is not available in btrfs, as of October 2015 at least.

This feature, known as per-subvolume raid levels, is commonly requested.

The official FAQ says this is planned for the future, but I haven't seen anything predicting when.

Related Solutions

Linux – Mount two btrfs subvolumes simultaneously

You could define the subvolume a that should act as root as default.
in this case it will automatically be mounted instead of the btrfs root.

Assuming your btrfs tree looks like this

/
|
|----a (subvolume containing / directory)
|
|----b (subvolume containing home directory)

in order to set a as default:

mount /dev/sda1 /mnt
btrfs subvolume create /mnt/a
btrfs subvolume set-default /mnt/a

now you can mount your btrfs filesystem and then the subvolume b

mount -o defaults /dev/sda1 /a
mount -o defaults,subvol=b /dev/sda1 /b

The fastest way to remove thousands of files on a btrfs filesystem

I would go the subvolumes route, myself. You just can't beat it for speed, and if you tilt your head and squint a bit, you can even say that it looks like the "right" way to store the files anyway...

Best Answer

Related Solutions

Linux – Mount two btrfs subvolumes simultaneously

The fastest way to remove thousands of files on a btrfs filesystem

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