I *think* it will work. The steps in the blog post to change the compaction strategy before RING_DELAY expires is to ensure no sstables are created before the strategy is changed.
But I think you will be venturing into unchartered territory where their might be dragons. And not the fun Disney kind. While it may be more work I personally would use one node in write survey to test LCS Cheers ----------------- Aaron Morton Freelance Cassandra Developer New Zealand @aaronmorton http://www.thelastpickle.com On 20/02/2013, at 6:28 AM, Henrik Schröder <skro...@gmail.com> wrote: > Well, that answer didn't really help. I know how to make a survey node, and I > know how to simulate reads to it, it's just that that's a lot of work, and I > wouldn't be sure that the simulated load is the same as the production load. > > We gather a lot of metrics from our production servers, so we know exactly > how they perform over long periods of time. Changing a single server to run a > different compaction strategy would allow us to know in detail how a > different strategy would impact the cluster. > > So, is it possible to modify org.apache.cassandra.db.[keyspace].[column > family].CompactionStrategyClass through jmx on a production server without > any ill effects? Or is this only possible to do on a survey node while it is > in a specific state? > > > /Henrik > > > On Tue, Feb 19, 2013 at 3:09 PM, Viktor Jevdokimov > <viktor.jevdoki...@adform.com> wrote: > Just turn off dynamic snitch on survey node and make read requests from it > directly with CL.ONE, watch histograms, compare. > > > > Regarding switching compaction strategy there’re a lot of info already. > > > > > > Best regards / Pagarbiai > Viktor Jevdokimov > Senior Developer > > Email: viktor.jevdoki...@adform.com > Phone: +370 5 212 3063, Fax +370 5 261 0453 > J. Jasinskio 16C, LT-01112 Vilnius, Lithuania > Follow us on Twitter: @adforminsider > Take a ride with Adform's Rich Media Suite > <signature-logo18be.png> > <signature-best-employer-logo6784.png> > > Disclaimer: The information contained in this message and attachments is > intended solely for the attention and use of the named addressee and may be > confidential. If you are not the intended recipient, you are reminded that > the information remains the property of the sender. You must not use, > disclose, distribute, copy, print or rely on this e-mail. If you have > received this message in error, please contact the sender immediately and > irrevocably delete this message and any copies. > > From: Henrik Schröder [mailto:skro...@gmail.com] > Sent: Tuesday, February 19, 2013 15:57 > To: user > Subject: Testing compaction strategies on a single production server? > > > > Hey, > > > Version 1.1 of Cassandra introduced live traffic sampling, which allows you > to measure the performance of a node without it really joining the cluster: > http://www.datastax.com/dev/blog/whats-new-in-cassandra-1-1-live-traffic-sampling > > That page mentions that you can change the compaction strategy through jmx if > you want to test out a different strategy on your survey node. > > That's great, but it doesn't give you a complete view of how your performance > would change, since you're not doing reads from the survey node. But what > would happen if you used jmx to change the compaction strategy of a column > family on a single *production* node? Would that be a safe way to test it out > or are there side-effects of doing that live? > > And if you do that, would running a major compaction transform the entire > column family to the new format? > > Finally, if the test was a success, how do you proceed from there? Just > change the schema? > > > /Henrik > >
