> drive on an EBS volume). Does that pattern look bad or is it > relatively normal? If it's not normal, any advice for what I should > change to get better performance?
Assuming you're running with the default cassandra VM options or similar (mainly, the CMS GC), the graph looks fairly normal to me. You would tend to expect frequent small variations that are the result of young-generation GC:s (ParNew:s), with some less frequent larger dips in memory usage associated with CMS completing a concurrent mark/sweep phase, typically triggered by used heap size approaching the current heap size. Normally the dips are somewhat indicative of the size of the actual live set that your application is using; I'm not sure what's going on in the middle of the graph with the dip being significantly higher. Did you have very significant write activity during that period (but it seems excessive even so). -- / Peter Schuller
