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The "MemtableThresholds" page has been changed by FlipKromer. http://wiki.apache.org/cassandra/MemtableThresholds?action=diff&rev1=13&rev2=14 -------------------------------------------------- It's much riskier to start tuning with this too high (a difficult-to-pinpoint malaise) than too low (easy to diagnose using JMX). Even for a high-end machine with say 48GB of ram, a 4GB heap size is reasonable initial guess -- the OS is much smarter than you think. For a rough rule of thumb, Cassandra's internal datastructures will require about {{{memtable_throughput_in_mb * 3 * number of hot CFs + 1G + internal caches}}}. - Also know that if you're running up against the heap limit under load that's probably a symptom of other problems -- diagnose those first. + Also know that if you're running up against the heap limit under load that's probably a symptom of other problems. Diagnose those first. == Virtual Memory and Swap == On a dedicated cassandra machine, the best value for your swap settings is no swap at all -- it's better to have the OS kill the java process (taking the node down but leaving your monitoring, etc. up) than to have the system go into swap death (and become entirely unreachable).
