Today I’d like to share a small yet valuable trick I had to learn while dealing with problems in the btrfs filesystem.
I switched to the filesystem about 8 months ago to better manage space allocation and shutdown times, as it should be quicker to recover upon errors. So far the filesystem performed admirably considering its reputation, but today I hit a nasty bug in the (behold) free space handling code.
Fiddling with large datasets, I managed to fill the whole volume, allocating chunks on the whole RAID1 configuration I setup. After removing the data though, things didn’t go as planned.