background http://wiki.apache.org/cassandra/FAQ#slows_down_after_lotso_inserts
Without more info my initial guess is some GC pressure and/or IO pressure from compaction. Check the logs for messages from the GCInspector or connect JConsole to the instance and take a look at the heap. Here is some info on looking at the IO stats http://spyced.blogspot.com/2010/01/linux-performance-basics.html With regard to the 25+GB on disk, that all depends on how much data you are writing. Be aware that compacted files are not immediately deleted http://wiki.apache.org/cassandra/FAQ#cleaning_compacted_tables You may also want to track things by looking at nodetool tpstats and cfstats (for latency). Cheers ----------------- Aaron Morton Freelance Cassandra Developer @aaronmorton http://www.thelastpickle.com On 21 Jul 2011, at 21:49, lebron james wrote: > Please help me solve one problem I have server with 4 GB RAM and 2x 4 cores > CPU When i start do massive writes in cassandra all works fine. but after > couple hours with 10K inserts per second database grows up to 25+ GB > performance go down to 500 insert per seconds I find out this because > compacting operations is very slow and i dont understand why, i set 8 > concurrent compacting threads but cassandra dont use 8 threads only 2 cores > are loaded.
