How to use OpsCenter to get the read Latency of a cluster?

Question

I have never used OpsCenter before. It seems OpsCenter can collect the performance matrics of a Cassandra cluster. But I just wonder other than viewing those matrics from a browser, may I get those matrics in a text file?

Answer 1

There is an api you can query http://docs.datastax.com/en/opscenter/6.0/api/docs/metrics.html#new-get-perf-data

Histogram metrics (what you should look at for latencies) are not straight forward to process though. Will probably want to look at https://github.com/apache/cassandra/blob/81f6c784ce967fadb6ed7f58de1328e713eaf53c/src/java/org/apache/cassandra/utils/EstimatedHistogram.java Its an array, which each value correspond to the buckets offsets in the EstimatedHistogram implementation.