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From Apache Wiki <>
Subject [Cassandra Wiki] Update of "PerformanceTuning" by FlipKromer
Date Tue, 31 Aug 2010 03:49:57 GMT
Dear Wiki user,

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The "PerformanceTuning" page has been changed by FlipKromer.


+ 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 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
  See and
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
  For starters, see "[[|Linux
Performance Basics for Cassandra]]".
- Also review the page on [[MemtableThresholds|Memtable Thresholds]].

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