On Mon, Sep 20, 2010 at 3:14 PM, Dathan Pattishall <[email protected]> wrote: > How do you set the compaction threshold from storage-conf.xml? is this > possible? > > What is the consensus on a basic Key-Value store of setting the > compactionthreshold min/max from > > ./nodetool --host=localhost --port=8181 getcompactionthreshold > Current compaction threshold: Min=4, Max=32 > > to say something like 2/5 ? > > > The next question is why do you want to change it? > > I noticed that all my outages are due to compaction. The SSTable count > grows from 4-11 and then a compaction happens taking that server > offline even with all the threshold tricks in cassandra.in.sh > (-Dcassandra.compaction.priority=1). So, playing with this value seems > to me to be the right course of action. >
You should look at your memtable settings memtable flushes happen because of either 1) time 2) size 3) activity Why are they happening for you? If you raise your memtable settings you will get larger memtables. This results in larger sstables that will compact less often. Lowering the compaction probably will not do what you want because this will result in the same data being compacted again and again. Remember the goal of minor compaction is to combine X like sized SSTables. If your nodes are going out during compaction they are likely overtaxed. I had great luck with the compaction priority. 6.5 features 'dynamic snitch' which should help lead traffic away from compacting nodes. You may want to give it a try.
