mongodb - "replication oplog window" possibly reduced due to profiling - when profiling disabled no change?
OK, i think i know the answer. The OPLOG collection is a capped collection. It overwrites over time. The profile level was set to 2 for a short period of time logging all operations. I guess it will take time to overwrite these operations on a capped collection again and as a result increase the op log window.

Would be interested in anyone elses take on this issue.

Thank you.