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.Jevdokimov@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

J. Jasinskio 16C, LT-01112 Vilnius, Lithuania
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From: Henrik Schröder [mailto:skrolle@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