Description of problem:
Add recommendation that under some workloads, it is beneficial to avoid log-based recovery and use backfill instead. This lets I/O proceed on objects being backfilled, since it occurs in the background. This is implemented by setting the min/max pg log size to 1 and 2.

This has a side effect of eliminating our duplicate op detection. To make this configuration robust, we need to keep a separate structure to detect duplicate ops.

Version-Release number of selected component (if applicable):


How reproducible:


Steps to Reproduce:
1.
2.
3.

Actual results:


Expected results:


Additional info:
https://bugzilla.redhat.com/show_bug.cgi?id=1461527