0.6.0 had some gc issues, (I think https://issues.apache.org/jira/browse/CASSANDRA-1014) if you see lots of gc collections in the logs, I'd give 0.6.1 a try, I found it much better.
Anecdotally, the sun jvm performs better than openJDK, and the u19 drop fixes some jvm bugs that can cause memory problems. Sun jvm, u19 (or higher) and Cassandra 0.6.1 fixed a lot of memory problems I ran into. From: James Golick [mailto:jamesgol...@gmail.com] Sent: Thursday, May 27, 2010 9:05 AM To: user@cassandra.apache.org Subject: Re: Continuously increasing RAM usage When I say unresponsive, I mean that latency becomes very high. Swap is turned off, but before I turned it on, it used to swap heavily at this point. Cassandra version is 0.6.0 Beta1 [cassandra1 ~]# java -version java version "1.6.0" OpenJDK Runtime Environment (build 1.6.0-b09) OpenJDK 64-Bit Server VM (build 1.6.0-b09, mixed mode) Here is the tpstats from a node that was restarted last night: http://gist.github.com/415987 On Thu, May 27, 2010 at 8:51 AM, Robert Coli <rc...@digg.com<mailto:rc...@digg.com>> wrote: On 5/26/10 11:32 PM, James Golick wrote: We're seeing RAM usage continually climb until eventually, cassandra becomes unresponsive. Given the handful of bugs related to memory bloat in specific versions of Cassandra combined with specific versions of JVMs, that information may be relevant to your question. What version are you running, and in what JVM environment? =Rob