cassandra cluster configuration for dev-container

John Sanda jsanda at redhat.com
Wed Apr 17 16:34:25 UTC 2013


If you are not working in or running out of the feature/cassandra-backend branch feel free to ignore this as the following info is specific to the feature/cassandra-backend branch right now.

There has been a good bit of infrastructure put in place for deploying a Cassandra cluster for automated tests and for the dev-container. When you build and deploy the dev-container, a cluster will automatically be deployed and started for you. There is nothing extra you have to do to get a functioning dev-container. That deployment code that is currently used was implemented well before rhqctl. The rhqctl script does not yet have support for dev-container deployments. I plan to update rhqctl so that it can be used for both prod and dev deployments. Then we have a common set of tools across deployments. The other benefit of using rhqctl is that it offers a lot more functionality than what is currently used for dev-container deployments.

We have been using out of the box heap settings for Cassandra. These are determined by the cassandra-env.sh script which is part of the Cassandra distro. There is no equivalent script for Windows so I'm not sure defaults are used with Windows. The cassandra-env.sh script will try to use 1/4 of your RAM for the heap; so, if you have 8 GB, it will give Cassandra 2 GB. For dev-container deployments and certainly for automated tests, we can get by with much smaller heaps.

I pushed some changes that lower the dev-container defaults and also make them configurable. The default max heap for the dev-container cluster nodes is now 512 MB. You can change this by editing rhq-server.properties before starting your dev-container for the first time after it has been (re)built. Uncomment and set the rhq.cassandra.max.heap.size and rhq.cassandra.heap.new.size properties. If you want to change the heap settings after the initial deployment, then you will need to edit <RHQ_HOME>/cassandra/node{0,1}/conf/cassandra-env.sh.

- John


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