Not 100% relevant but I found this to be interesting if you're nodes are doing heavy disk I/O:
http://rackerhacker.com/2008/08/07/reduce-disk-io-for-small-reads-using-memory/ -Chris On Jul 15, 2010, at 11:47 PM, Peter Schuller wrote: >> This would require that Cassandra run as root on Linux systems, as 'man >> mlockall' states: > > IIRC, mlock() (as opposed to mlockall()) does not require root > privileges - but is subject to resource limitations. > > However, given a lack of control of how memory is allocated in the JVM > I suppose mlock() is probably not very useful. > >> http://andrigoss.blogspot.com/2008/02/jvm-performance-tuning.html >> >> Basically when mmapping using HUGETLB you don't have to be root, but your >> memory ends up being effectively locked, so that would prevent the swapping, >> and might have the added bonus of slightly faster memory allocation/access. > > Very nice, especially since it doesn't require native code/tricks. I > imagine the need for contiguous space could be a practical annoyance > though. Has anyone tried this specifically with cassandra? > > -- > / Peter Schuller
