On 10/03/2021 12:07, telsch wrote: > Dear devs, > > after my root partiton was full, i deleted the last monthly snapshots. > however, no memory was freed. > so far rebalancing helped: > > btrfs balance start -v -musage=0 / > btrfs balance start -v -dusage=0 / > > i have deleted all snapshots, but no memory is being freed this time.
Don't forget that, in general, deleting a snapshot does nothing - if the original files are still there (or any other snapshots of the same files are still there). In my experience, if you *really* need space urgently you are best of starting with deleting some big files *and* all the snapshots containing them, rather than starting by deleting snapshots. If you are doing balances with low space, I find it useful to watch dmesg to see if the balance is hitting problems finding space to even free things up. However, one big advantage of btrfs is that you can easily temporarily add a small amount of space while you sort things out. Just plug in a USB memory stick, and add it to the filesystem using 'btrfs device add'. I don't recommend leaving it as part of the filesystem for long - it is too easy for the memory stick to fail, or for you remove it forgetting how important it is, but it can be useful when you are trying to do things like remove snapshots and files or run balance. Don't forget to use btrfs device remove to remove it - not just unplugging it!
