- Using FTP, export the config files from both primary and secondary controllers to a remote PC
- Make sure the replacement controllers are running the same firmware revision as the original pair.
- "Approve As Foreign" all AP's from the secondary controller, release them to the primary, and approve them as local.
- Break availability, under Controller tab > Administration Dropdown > Availability and click stand alone.
- Power down the secondary controller, and provision one replacement controller with the secondaries IP address.
- Setup availability between the original primary and the replacement, with the original primary remaining as master.
- Ensure you have a backup tunnel for AP failover under Reports> AP availability, and release the APs from the original master to the new secondary, approving them as local.
- Repeat this process replacing the old primary with the new replacement, and setup high availability, setting the secondary as the primary of the new pair to push the config to the new secondary.