Oracle High Availability & Disaster Recovery
RAC, Data Guard, RMAN, failover & recovery
High availability and disaster recovery are two different promises, and conflating them is how teams end up paying for one while believing they have the other. RAC keeps a database serving when a node fails; Data Guard keeps your data alive when a site or its storage fails; RMAN is the floor under both — the backup you can actually restore. Most production estates need a deliberate combination, not a default. These guides work through the decisions — RAC vs Data Guard vs both, switchover vs failover, why nodes get evicted, and how to prove your standby actually works — read from the logs up, with runnable and forensic labs you can try yourself.
Guides in this pillar
- Oracle RMAN Recovery Runbook: Restore, Recover, Prove It
Restore rebuilds datafiles; recover rolls them forward. The RMAN runbook for a lost datafile, controlfile, bad DELETE, or corrupt block — proven, not hoped. - Data Guard Switchover vs Failover: Which Role Transition, and When
Switchover is a planned zero-loss role swap; failover is for when the primary is gone — plus Fast-Start Failover, protection modes, and the mistakes to avoid. - RAC Node Eviction: A Troubleshooting Checklist That Starts With "Why"
Oracle RAC node eviction from the logs up: the three heartbeats, misscount vs disktimeout, split-brain and voting disks, and a checklist to find the real cause. - The Oracle HA Decision Tree: RAC vs Data Guard vs Both
RAC survives node failure; Data Guard survives site loss; only backups survive a bad DELETE. A RAC-vs-Data-Guard decision framework with RTO/RPO and a free lab.