Thanks Aaron, I hear you on the unchartered territory bit, we're definitely not gonna risk our live data unless we know it's safe to do what we suggested. :-) Oh well, I guess we'll have to setup a survey node instead.
/Henrik On Thu, Feb 21, 2013 at 4:54 AM, aaron morton <aa...@thelastpickle.com>wrote: > 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<http://twitter.com/#!/adforminsider> >> Take a ride with Adform's Rich Media Suite<http://vimeo.com/adform/richmedia> >> <signature-logo18be.png> <http://www.adform.com/> >> <signature-best-employer-logo6784.png> >> <http://www.adform.com/site/blog/adform/adform-takes-top-spot-in-best-employer-survey/> >> >> 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**** >> > > >
