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 (deleteNode procedure)
- Upgrade the OS (which is most likely a reimaging of the node). If the OS upgrade does not wipe out the entire server you can follow MOS Note:1559762.1 as it shows an OS upgrade from OL 6.2 to 6.4 which leave the Oracle installations intact)
- Add Node 1 back to the cluster (addNode procedure)
- Extend the Database Home to Node 1 using either cloning or addNode
- Make the database available on the newly added Node 1 and drain Node 2
- Repeat steps 2-6 for Node 2
- Ideally now you’ll perform a rolling upgrade of Oracle GI to Oracle Database 12c. Please apply the most recent PSU as well.
- Furthermore you may now look into upgrading your databases to Oracle Database 18.104.22.168 as well.
See the following documentation:
- Adding and Deleting Oracle RAC from Nodes on Linux and UNIX Systems
- Cloning Oracle RAC to Nodes in a New Cluster
- Using Cloning to Add Nodes to a Cluster