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The "PerformanceTuning" page has been changed by FlipKromer. http://wiki.apache.org/cassandra/PerformanceTuning?action=diff&rev1=5&rev2=6 -------------------------------------------------- + Be sure to review the page on [[MemtableThresholds|Memtable Thresholds]] -- several important configuration and system settings are described there. + + === Lessen overall system impact of Compactions === To lower compaction priority (thus reducing its impact on the rest of the system, and making it take longer), add these options to cassandra.in.sh in 0.6.3 or later: {{{ @@ -7, +10 @@ -XX:ThreadPriorityPolicy=42 \ -Dcassandra.compaction.priority=1 \ }}} - - Useful JVM options: + === Useful JVM options === - {{{ -XX:+UseCompressedOops # enables compressed references, reducing memory overhead on 64bit JVMs }}} - See http://wikis.sun.com/display/HotSpotInternals/CompressedOops and http://publib.boulder.ibm.com/infocenter/javasdk/v6r0/topic/com.ibm.java.doc.diagnostics.60/diag/understanding/mm_compressed_references.html for discussion on the Sun and IBM JVMs, respectively. Compressed references (aka OOPs = ordinary object pointers) are not stable for Sun JVM versions before 6u19. + == System Settings == todo: describe how top, iostat -x, and JMX stats can help you see what is making things slow For starters, see "[[http://spyced.blogspot.com/2010/01/linux-performance-basics.html|Linux Performance Basics for Cassandra]]". - Also review the page on [[MemtableThresholds|Memtable Thresholds]]. -
