In hbase region and regionserver metrics I cannot understand the relationships between metrics related to read requests, get and scanNext operations.
The hbase.regionserver.readRequestCount is documented here <https://hbase.apache.org/book.html#rs_metrics> as: hbase.regionserver.readRequestCount The number of read requests received In addition to that, there are also get_num_ops and scanNext_num_ops metrics. I cannot find an official documentation for them. They are mentioned in this ticket <https://issues.apache.org/jira/browse/HBASE-15376>. In the metrics I see, the readRequests are orders of magnitude larger than the sum of all get and scanNext requests in one regionserver. For example:[image: ReadGetScanMetrics] <https://i.stack.imgur.com/3fyGk.png> Please note that the y-axis is in log scale. The plots are using these Wavefront queries ReadRequestRate sum(rate(ts(hbase.regionserver.server.readRequestCount, source="*<sourceSelector>*" ))) GetNumRate sum(rate(ts(hbase.regionserver.regions.get_num_ops, source="*<sourceSelector>*"))) ScanNumRate sum(rate(ts(hbase.regionserver.regions.scanNext_num_ops, source="*<sourceSelector>*" ))) What may be the reason of that huge delta ? What does readRequest counter include in addition to get and scanNext operations ? Some unproven theories of mine. 1. Maybe the readRequests counter increments for each row read during a scanNext call ? 2. Maybe the readRequest counter increments with async replication jobs, region replication, cross datacenter replication etc. Note this is running HBase 1.2.0-cdh5.11.0 You can see this question also in server fault, if you like to see a different formatting. https://serverfault.com/q/973638/428655 Thanks Hakan
