Hey there,
I have the exact same problem with a single mongo instance.
I’m doing many bulkWrites one after the other and in parallel and for some cases the file size increases until the entire disk gets full and Mongo crash.
I think me and many others need a more definite answer on how can I tell how much writing operation could cause this and how to limit my load on mongo, it’s really hard to just “guess” the numbers here. Also I think it’s weird that mongo can’t handle the load in a better way or clear this file after the load has finished.