JBoss ON storage node log indicates GCInspector.java reports Heap is full and you may need to reduce memtable and/or cache sizes

Issue

• rhq-storage.log includes repeated WARN messages:

  GCInspector.java (line 142) Heap is 0.7637708699279387 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
  StorageService.java (line 3616) Flushing CFS(Keyspace='rhq', ColumnFamily='raw_metrics') to relieve memory pressure
  GCInspector.java (line 142) Heap is 0.7517777149403199 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
  StorageService.java (line 3729) Flushing CFS(Keyspace='rhq', ColumnFamily='aggregate_metrics') to relieve memory pressure
  

• OutOfMemoryError: Java heap space in rhq-storage.log:

  ERROR [FlushWriter:1] ... CassandraDaemon.java (line 193) Exception in thread Thread[FlushWriter:1,5,main] 
  java.lang.OutOfMemoryError: Java heap space