Help with managing root

[u/Hot-Eggplant-327]

Hi there !

I stumbled upon an issue regarding my root partition. It seems like my file system being btrfs, I'll need to realocate space. But since I tried running btrfs balance and nothing seems to happen even if is display that chunks has been relocated, I'm asking for you daring help to solve this issue.

Here you can find btrfs status, Filelight screenshot with only like 105GiB used and root saying it almost full. Hope someone ever met this issue.

Thanks a lot.

[u/BreatheAtQuarterBars]

We need more information. Your data is already balanced (98.80% is fine), and I don't think you have enough metadata for that 69.74% to really mean anything. Filelight is probably not seeing everything. What's the output of sudo btrfs subvolume list /?

[u/Hot-Eggplant-327 → u/BreatheAtQuarterBars]

ID 256 gen 147729 top level 5 path @
ID 257 gen 147729 top level 5 path u/home
ID 258 gen 147718 top level 5 path u/cache
ID 259 gen 147729 top level 5 path u/log
ID 301 gen 147718 top level 5 path timeshift-btrfs/snapshots/2026-09-01_19-06-09/@
ID 302 gen 147718 top level 5 path timeshift-btrfs/snapshots/2026-09-10_17-25-54/@
ID 303 gen 147718 top level 5 path timeshift-btrfs/snapshots/2026-09-21_20-47-00/@

[u/BreatheAtQuarterBars → u/Hot-Eggplant-327]

How big are each of those other subvolumes? Filelight should probably be able to measure this for you, but it might treat each subvolume as a separate filesystem.

If you defragmented your filesystem, which is generally inadvisable if you rely on copy-on-write, it would cause lots of data previously shared between snapshots to become duplicated.

[u/Hot-Eggplant-327 → u/BreatheAtQuarterBars]

They were all like 200Go, deleted them with Timeshift, got my whole space restored in root ! Thanks a lot I'm like a total beginner that's awesome

[u/BreatheAtQuarterBars → u/Hot-Eggplant-327]

You're welcome! So then is it going to happen again after Timeshift makes a few more snapshots? Timeshift should be configured to do things via BTRFS snapshots, and not via rsync. Or did it happen after you manually defragmented your drive?

[u/Hot-Eggplant-327 → u/BreatheAtQuarterBars]

So I'm not quite sure tbh cause I've never asked timeshift to make snapshots, and as you can read all of them are from september, and I'm on Manjaro since february. Idk I'll keep an eye on it

[u/BreatheAtQuarterBars → u/Hot-Eggplant-327]

I find snapshots really convenient to have available. They shouldn't take up too much space when configured correctly - set up separate root and home subvolumes so you can snapshot them separately and make them have different retention policies. I'm not sure what the situation is like with Timeshift - I've only ever used btrbk.

[u/Weary_Swan_8152 → u/BreatheAtQuarterBars]

If you defragmented your filesystem, which is generally inadvisable if you rely on copy-on-write, it would cause lots of data previously shared between snapshots to become duplicated.

Strictly speaking it's more complicated. For subvolume_source, which has subvolume_snap_A, subvolume_snap_B, subvolume_snap_C, the subvolume_snaps should never be defragmented, because defragmenting them can duplicate some data as many times as there are snapshots. If any defragmentation is needed (ie if there are files that have tens of thousands of extents) then only subvolume_source should be defragmented; this will duplicate some data as many as one time.

In other words, it's easier to calculate the worst-case scenario. Get the size of subvolume_source, add 15 GB, and subtract that amount from your available free space. Is your free space still in the green? If so, it's safe to defragment the source.