Edit: Solved!
Unfortunately I’m not sure exactly what fixed it, because I was running btrfs commands like a madman.
Some combination of the following caused my 100GB labelled as UNREACHABLE to turn into UNUSED, which allowed that space to be written to as normal:
sudo btrfs balance start -v /
sudo btrfs filesystem defrag -v /
sudo btrfs filesystem defrag -v -r /
Also the tool btdu was incredibly helpful!
One of my linux boxes ran out of disk space, which surprised me, because it definitely didn’t have that much stuff on it. When I check with df it says I have used 212GB on my / path:
$ df -h /
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 227G 212G 5.2G 98% /
So, I tried to use du to see if maybe a runaway log file was the cause, but this says I have only used 101GB on my / path (this is also more in-line with how much space I expected to be used):
$ du -h | sort -h
...
101G /
Using those commands with sudo outputs the same sizes.
My filesystem is Btrfs, I’ve tried the suggestion to use btrfs balance start ... but this actually INCREASED my disk usage to 99% lol
So my question is… what on earth is using the remaining 111GB?? Why can I not see it in du?
There could be btrfs stuff I’m not aware of, but on a file system structure level, do you have a separate drive for booting and then another you added and mounted separately? Or did you install Linux over another install and changed partitions used? The reason I’m asking is you could have a whole drive of data under a folder and then later mount another partition or drive to that same folder. Linux will show you the mounted folder contents, but the original is not visible until you unmount your Mount point. The data is still there. So drive can be full, even though contents look smaller.
I can’t say its that for sure, but it has tripped people up before.
But could be btrfs cleanup needs looking at.
Just one drive, it was a clean Linux install with no funky stuff going on. I’ll have to look into Btrfs cleanup more, last time I did it the disk just filled up even more
Yeah, I haven’t dealt with that much since OpenSUSE has all the cleanup and maintenance scheduled.
Is your whole drive BTRFS even your /Home on same partition? The BTRFS subvolumes share a pool if setup as one, and filling up home subvolume also fills up your system subvolume, since its shared.
I sometimes use btrf assistant, it’s a gui helper for btrfs, shows some helpful hints, there’s balancing, scrubbing, snapshot cleanup. I should learn more about it all, but it helped a ton with figuring out what’s going on with all my space.