Any idea about the steps to be followed to add storage space to postgres cluster in openshift/ k8 enviroment?
Postgresql only cares about the size of the mount point, not how you resize it.
Resizing that mount point is a job for the System Administrator, and depends on the filesystem, whether lvm, etc. If you don't know how to do that, Unix.StackExchanche.com probably does. The OpenShift mailing list certainly does.
