When upgrading from 5.6 to 6.1 (and then to 6.8), we have noticed an increase in memory usage. Before and after the upgrade, JVM heap size was configured at 3GB. After the upgrade, overall system memory usage jumped from 3.3GB to 4.2GB. ES nodes are hosted on machines with 6GB of memory.
We are noticing occasional bursts of IO, correlated with spikes in search latencies. We suspect it is because of the increase in memory usage.
Does the community have any insight into the increase in memory usage of v6?