Last week at the upgrade workshop in Budapest a customer had a interesting and – I believe – not uncommon question.
“How can I upgrade my Linux Operating System in my RAC environment without taking the entire cluster down?”
In this specific case the customer wanted to upgrade from RHEL 5.10 to RHEL6 or RHEL7.
Let’s assume it’s the typical 2-node-RAC where one wants to upgrade in a rolling fashion. And the data is stored within ASM.
- Drain Node 1 (i.e. take the workload off) – this will be the node getting upgraded first
- Remove Node 1 from the cluster