We have a 3 node cluster (running 4.1.1-5914 Enterprise Edition), and each node is displaying the msg "Metadata overhead warning. Over 85% of RAM allocate to … is taken up by keys and metadata. In addition, each of our clients (Java SDK) are receiving the exception “Exception occurred: com.couchbase.client.java.error.TemporaryFailureException”. In addition, the “active docs resident %” is near 0 (0.00002), which is fine and what we would expect for a large system.
Thus the question is, “is it a hard requirement that ALL keys and metadata must fit into RAM at all times”? Note that in our system we retain a very large amount of “old data” that can be queried (via views) by the end user, but those queries are executed very infrequently (and performance is not a priority for those queries). Thus, the ability to retain the most frequently used “keys and metadata” in memory, and allow the “less frequently used keys and metadata” to reside on disk (SSDs) is the behavior needed. Is there a way to configure Couchbase to access the disk for “keys and metadata that are used infrequently”?