Hi, I'm using a 2 node cluster in production ( 2 EC2 c1.medium, CL.ONE, RF = 2, using RP)
1 - I got this kind of message quite often (let's say every 30 seconds) : WARN [ScheduledTasks:1] 2012-05-15 15:44:53,083 GCInspector.java (line 145) Heap is 0.8081418550931491 full. You may need to reduce memtable and/or cache sizes. Cassandra will now flush up to the two largest memtables to free up memory. Adjust flush_largest_memtables_at threshold in cassandra.yaml if you don't want Cassandra to do this automatically WARN [ScheduledTasks:1] 2012-05-15 15:44:53,084 StorageService.java (line 2645) Flushing CFS(Keyspace='xxx', ColumnFamily='yyy') to relieve memory pressure Is that a problem ? 2 - I shared 2 screenshot the cluster performance (via OpsCenter) and the hardware metrics (via AWS). http://img337.imageshack.us/img337/6812/performance.png http://img256.imageshack.us/img256/9644/aws.png What do you think of these metrics ? Are frequents compaction normal ? What about having a 60-70% cpu load for 600 Reads&Writes/sec with this hardware ? Is there a way to optimize my cluster ? Here you got the main points of my cassandra.yaml : flush_largest_memtables_at: 0.75 reduce_cache_sizes_at: 0.85 reduce_cache_capacity_to: 0.6 concurrent_reads: 32 concurrent_writes: 32 commitlog_total_space_in_mb: 4096 rpc_server_type: sync (I am going to switch to hsha, because we are using ubuntu) #concurrent_compactors: 1 (commented, so I use default) multithreaded_compaction: false compaction_throughput_mb_per_sec: 16 rpc_timeout_in_ms: 10000 others tuning options (as many of the ones above) are default. Any advice or comment would be appreciated :). Alain
