User talk:Gertp

Generic active/passive clusters

Configuring a cluster using corosync and heartbeat involves you having to write a start/stop and monitoring script for the service you are building the cluster for.

This script is very much like an "init.d" script, but you can't directly use an init.d script as heartbeat scripts use tri-state logic in stead of two-state logic. I.e., heartbeat controlled services are "running", "stopped" or "failed", whereas services controlled by init that fail are stopped and must be restarted. Heartbeat uses the third state "failed" as the trigger to migrate the service to another node in your services pool.

For a simple service consisting of one process, monitoring is easy and adaptation of an existing init.d script straighforward. Hint: use the sample

    /usr/lib/ocf/resource.d/heartbeat/Dummy

as a starting-point.

For services comprised of two or more processes, you'll have to loop over all processes, their pid and lock files to see whether processes are running and correspond to the lock and pid files. Assuming that all processes are well behaved and store pid and lock files in the standard locations.

The

Install the cluster engine & resource manager

You need to perform the installation on each cluster node.

Add the EPEL repo to /etc/yum.repos.d:

    # rpm -Uhv http://download.fedora.redhat.com/pub/epel/5/x86_64/epel-release-5-4.noarch.rpm 

Add the Clusterlabs repo to /etc/yum.repos.d:

    # wget -O /etc/yum.repos.d/pacemaker.repo http://clusterlabs.org/rpm/epel-5/clusterlabs.repo

Now have yum install the cluster engine and resource managers. This will install loads of dependencies:

    # yum -y install pacemaker