If you’re running an HBase cluster in production, you’ve probably noticed that HBase shares a number of useful metrics about everything from your block cache performance to your HDFS latencies over JMX (or Ganglia, or just a file). The problem is that it’s sometimes hard to know what these metrics mean to you and your users. Should you be worried if your memstore SizeMB is 1.5GB? What if your regionservers have a hundred stores each? This talk will explain how to understand and interpret the metrics HBase exports. Along the way we’ll cover some high-level background on HBase’s internals, and share some battle tested rules-of-thumb about how to interpret and react to metrics you might see.