There is some additional memory usage in the JVM beyond that Heap size, in the permanent generation. 900mb sounds like too much for that, but you can check by connecting with JConsole and looking at the memory tab. You can also check the heap size there to see that it's under the value you've set. 

Check you are using standard disk access (in conf/cassandra.yaml) rather than memory mapped access. However the memory mapped memory is reported as virtual memory, not resident. So I'm just mentioning it to be complete.

If you think you've configured things correctly and the JVM is not behaving (which is unlikely) please include some information on the JVM and OS versions and some hard numbers about what the process is using.

Hope that helps.

On 5/03/2011, at 9:51 AM, Casey Deccio wrote:

On Fri, Mar 4, 2011 at 11:03 AM, Chris Burroughs <> wrote:
What do you mean by "eating up the memory"?  Resident set size, low
memory available to page cache, excessive gc of the jvm's heap?

jvm's heap is set for half of the physical memory (1982 MB out of 4G), and jsvc is using 2.9G (73%) of resident memory.

Are you saying: that you want a smaller heap and what settings to change
to accommodate that, or that you have already set a small heap of x and
Cassandra is using significantly more than that?

Based on my observation above, the latter.