I wouldn't go above 8G unless you have a very powerful machine that can keep the GC pauses low.
Sent from my iPhone > On Mar 12, 2014, at 7:11 PM, Edward Capriolo <edlinuxg...@gmail.com> wrote: > > That is too much ram for cassandra make that 6g to 10g. > > The uneven perf could be because your requests do not shard evenly. > > On Wednesday, March 12, 2014, Batranut Bogdan <batra...@yahoo.com> wrote: > > Hello all, > > > > The environment: > > > > I have a 6 node Cassandra cluster. On each node I have: > > - 32 G RAM > > - 24 G RAM for cassa > > - ~150 - 200 MB/s disk speed > > - tomcat 6 with axis2 webservice that uses the datastax java driver to make > > asynch reads / writes > > - replication factor for the keyspace is 3 > > > > All nodes in the same data center > > The clients that read / write are in the same datacenter so network is > > Gigabit. > > > > Writes are performed via exposed methods from Axis2 WS . The Cassandra Java > > driver uses the round robin load balancing policy so all the nodes in the > > cluster should be hit with write requests under heavy write or read load > > from multiple clients. > > > > I am monitoring all nodes with JConsole from another box. > > > > The problem: > > > > When wrinting to a particular column family, only 3 nodes have high CPU load > > ~ 80 - 99 %. The remaining 3 are at ~2 - 10 % CPU. During writes, reads > > timeout. > > > > I need more speed for both writes of reads. Due to the fact that 3 nodes > > barely have CPU activity leads me to think that the whole potential for C* > > is not touched. > > > > I am running out of ideas... > > > > If further details about the environment I can provide them. > > > > > > Thank you very much. > > -- > Sorry this was sent from mobile. Will do less grammar and spell check than > usual.
