Steve- I would probably design the experiment to test different cluster sizes as completely independent. That means, taking the entire thing down and back up again (possibly even rebooting the boxes, and/or re-initializing the cluster at the new size). I'd also do several runs while it is up at a particular cluster size, to capture any performance difference between the first and a later run due to OS or TServer caching, for analysis later.
Essentially, when in doubt, take more data... --L On Fri, Aug 3, 2012 at 5:50 PM, Steven Troxell <steven.trox...@gmail.com> wrote: > Hi all, > > I am running a benchmarking project on accumulo looking at RDF queries for > clusters with different node sizes. While I intend to look at caching for > each optimizing each individual run, I do NOT want caching to interfere for > example between runs involving the use of 10 and 8 tablet servers. > > Up to now I'd just been killing nodes via the bin/stop-here.sh script but I > realize that may have allowed caching from previous runs with different node > sizes to influence my results. It seemed weird to me for exmaple when I > realized dropping nodes actually increased performance (as measured by query > return times) in some cases (though I acknowledge the code I'm working with > has some serious issues with how ineffectively it is actually utilizing > accumulo, but that's an issue I intend to address later). > > I suppose one way would be between a change of node sizes, stop and restart > ALL nodes ( as opposed to what I'd been doing in just killing 2 nodes for > example in transitioning from a 10 to 8 node test). Will this be sure to > clear the influence of caching across runs, and is there any cleaner way to > do this? > > thanks, > Steve
