add, remove; how about merge?

I am new at this btrfs stuff!

As I understand it, you can add a physical disk or partition and have data spread into the new space. You can also move data off a disk or partition and then remove it.

Has any though been given to being able merge to existing (separate) btrfs "volumes" into a single volume?

Alternatively, how about at tool for transfering a subvolume from one pool to another? I tried using fsarchiver but that did not work out too well.

Gene

This would be difficult to do in kernel space -- you'd have to
change the UUIDs on all the metadata on at least one of the filesystems, plus handle (correctly) all of the numberspace clashes correctly -- subvolume trees, virtual address space, and probably a load that I've forgotten as well. Given what I'm about to say, I can't see this happening any time soon.

You want send/receive. It's in the mainline kernel, and you'll need
a recent userspace, but it allows you to transfer subvolumes cleanly and losslessly between filesystems.

Hugo.

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I think thats possible with btrfs-send/receive

Remco