I have 3 Couchbase servers in a cluster. They are only used for couchbase. All (virtuell) machines have the same specs. The specs per machine are 4GB RAM; 2 cores Intel Xeon. Each server preserves 1.2GB RAM for Couchbase documents. 1.2GB of 4GB is about 30%. But usage is way higher.
What would happen if I double the RAM of each machine (4GB -> 8GB)? Will the usage go up to 90% again? Is this expected bahaviour?
More details: there are no disk fetches, all documents are still in RAM. There were not many operations per second while taking the screenshot. The servers more or less idle.