I used cassandra driver provided by datastax (3.5.0) library in nodejs. I've 5 nodes cluster. I'm writing to a table with quorum.
I observed that there is some spike in write. In ~20 writes, 2-5 writes are taking longer(~200ms). I debugged one of the node process with strace and found that longer latencies are batched and they use same fd to connect to cassandra. This may be the multiplexing.
Why it takes that long ?
Where should I look to resolve it?