On Sun, Mar 1, 2020 at 7:38 PM Rich Rauenzahn <rrauenza@xxxxxxxxx> wrote: > > On Sun, Mar 1, 2020 at 5:57 PM Chris Murphy <lists@xxxxxxxxxxxxxxxxx> wrote: > > >But I still don't get why it wouldn't move blocks from the full drives... > > > > To where? There's only one drive with unallocated space. > > ...but that's what I'd expect the balance to do? If Block (Chunk?) A > is on, say device 1 (4TB) and device 2 (2TB), why wouldn't it move > Block A to the new drive from device 1 or 2 in order to free up space > and balance/spread out usage across the drives? That isn't how balance works on Btrfs. To do a balance on raid1 it means reading a 1GiB chunk, and writing 1GiB *into empty space* on drive X and 1GiB *into empty space* on drive Y. And then only after that succeeds is the original 1GiB chunk (1GiB each on two devices) freed. No such thing as move. Everything is a copy. > OH! Just checked -- the balance finally cancelled after freeing up the 150GB. OK good. At this point it should have the head room to do the balance. It still might be slower than it would be if it had say 25% free space on the original three drives. -- Chris Murphy
