Access Scanner is disabled per-bucket if Resident Ratio is high enough

In Couchbase Server 4.5.0 (MB-11418) a change was introduced so that if the Resident Ratio (both Active and Replica) is above 95%, the Access Logs for a bucket will be deleted and the Access Scanner will not run. The same check is performed every day and the Access Scanner will run if the RR falls below 95% again.

This has the benefit that if the RR is high enough, the CPU-intensive task can be skipped, the reasoning being that the Access Logs actually hinder warmup with such a high Resident Ratio.

This should be documented at least under Initialization and Warmup, but is also relevant to sizing and performance (for example the Access Scanner can delay Index updates as it shares the AuxIO thread pool with the projector which can become saturated on low-CPU core hosts).