> If not, maybe I just generate the same 1,000,000 files on each machine, then > randomly delete 1/2 the files and stream them from the other machine as > writing those files would all be in random locations again forcing a much > worse measurement of MB/sec I would think. Not sure I understand the question. But you could just scrub the data off a node and rebuild it.
Note that streaming is throttled, and it will also generate compaction. > He has twenty 1T drives on each machine and I think he also tried with one 1T > drive seeing the same performance which makes sense if writing sequentially Are you using the 1.2 JBOB configuration? Cheers ----------------- Aaron Morton Freelance Cassandra Consultant New Zealand @aaronmorton http://www.thelastpickle.com On 1/04/2013, at 11:01 PM, "Hiller, Dean" <dean.hil...@nrel.gov> wrote: > (we plan on running similar performance tests on cassandra but wanted to > understand the raw foot print first)….. > > Someone in ops was doing a test transferring 1T of data from one node to > another. I had a huge concern I emailed him that this could end up being a > completely sequential write not testing random access speeds. He has twenty > 1T drives on each machine and I think he also tried with one 1T drive seeing > the same performance which makes sense if writing sequentially. Does anyone > know of something that could generate a random access pattern such that we > could time that? Right now, he was measuring 253MB / second from the time > it took and the 1T of data. I would like to find the much worse case of > course. > > If not, maybe I just generate the same 1,000,000 files on each machine, then > randomly delete 1/2 the files and stream them from the other machine as > writing those files would all be in random locations again forcing a much > worse measurement of MB/sec I would think. > > Thoughts? > > Thanks, > Dean
