Out of nowhere the two secondary instances for a three node cluster with very little CPU usage spiked to 100% and remained high.

Version: 2.4.14

Things we did so far:

• Rebuilt all three databases from replicas.
• reIndex()

Things we discovered:

Now that the load is higher and avg response time is >100ms than usual we see some query that should be using index not using it.

Tue Feb 19 12:47:27.946 [conn11958] query locator.pages query: { query: { _depth:

, _site: "sample.com" }, orderby: { _id: 1 } } ntoreturn:0 ntoskip:0 nscanned:2106803 keyUpdates:0 numYields: 11 locks(micros) r:5514254 nreturned:30 reslen:130866 2951ms

Screenshots

Secondary Node 1 - The other follows the same pattern.

Primary Node (mostly idle except for nightly batch loads)