@MichelDiz I think I have a solution to my problem:
Dgraph sets by default 7 compaction levels (1 memory level and 6 on-disk levels) and the base level size to 10 MiB with a multiplier of 10. So the maximum size of the 6 on-disk levels should be as follows:
1 → 10 MiB
2 → 100 MiB
3 → 1 GiB
4 → 10 GiB
5 → 100 GiB
6 → 1 TiB
Dgraph panics in my case after it grows to ~1.1 TiB, which are roughly the 6 levels combined. After I set --badger "maxlevels=8", Dgraph compacted a lot of data from level 6 to the new 7th level and now it works again. I could also probably have increased the base level instead.
Can somebody from the Dgraph team confirm if my reasoning is correct? If yes, there should be a note in the docs that if data grows over 1 TiB the default values have to be modified.