Which Cassandra version are you on? Essentially heap size is function of number of keys/metadata. In Cassandra 1.2 lot of the metadata like bloom filters were moved off heap.
On Tue, Oct 1, 2013 at 9:34 PM, srmore <comom...@gmail.com> wrote: > Does anyone know what would roughly be the heap size for cassandra with > 1TB of data ? We started with about 200 G and now on one of the nodes we > are already on 1 TB. We were using 8G of heap and that served us well up > until we reached 700 G where we started seeing failures and nodes flipping. > > With 1 TB of data the node refuses to come back due to lack of memory. > needless to say repairs and compactions takes a lot of time. We upped the > heap from 8 G to 12 G and suddenly everything started moving rapidly i.e. > the repair tasks and the compaction tasks. But soon (in about 9-10 hrs) we > started seeing the same symptoms as we were seeing with 8 G. > > So my question is how do I determine what is the optimal size of heap for > data around 1 TB ? > > Following are some of my JVM settings > > -Xms8G > -Xmx8G > -Xmn800m > -XX:NewSize=1200M > XX:MaxTenuringThreshold=2 > -XX:SurvivorRatio=4 > > Thanks ! >
