Not sure this idea holds a ton of water, but wanted to put it out there for consideration.....

It would be a good testing tool to be able to have a recording of a workload that could be played in a loop which also does a rich variety of operations.

The current problem with mongotape workloads is that they require a "clean" set of data at restart, or must be read-only.

It seems possible to create a workload that combines both reads and writes by making sure that the reads are range queries (not targeting specific values) and the writes idempotent ($set, etc.) and make the collections in use be TTL or capped collections to limit their size. This would also make it possible to start the workload from an empty server.

This workload could be used to test things like FTDC, or put into use as a longevity test. The advantage of using mongotape over a simple workload generator is that the workload could easily be sped up or throttled as necessary.