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Thursday, March 01, 2012

Setting up an Apache cluster under RedHat Enterprise Linux

If it ever happens that you have to set up an Apache Linux cluster, I highly recommend the step-by-step manual from clusterlabs.org.
The docs are really easy to read and are very helpful.
I only have two negative points:

  1. Sometimes the commands you have to enter into the console are not clearly separated from the parameters or text you have to pass. Example:
    cat <<-END >>/etc/corosync/service.d/pcmkservice {
            # Load the Pacemaker Cluster Resource Manager
            name: pacemaker
            ver:  1
    }
    END
    The file to create is called /etc/corosync/service.d/pcmk (NOT pcmkservice) and the content of the file starts with "service {
    # Load the Pacemaker ..."
    I assume this has something to do with the formatting of the docs.
  2. The docs almost never tell you what to do in case things go wrong or you did a typo or your environment differs from the one used in the docs.
    In that case you have to use google and cross your fingers or use other resources like this one.
After all I only had to consult google once during the complete setup.
My failover tests succeeded after a few hours of setup including writing a howto for my specific setup.
Now the cluster works using corosync and pacemaker as services.