Database and Application Migration to OCI
This domain tests how you move databases and application tiers with the right tool for the downtime and heterogeneity constraints. The exam expects tool selection by RTO/RPO, platform, version, and size.
Core rules
- For Oracle databases, match the method to downtime: Data Pump for small or offline moves; RMAN backup/restore for physical clones; Data Guard for physical standby and switchover; GoldenGate for minimal-downtime and heterogeneous replication; ZDM to automate physical or logical online migration.
- Check endianness, database version, and character set before choosing physical methods. Cross-platform or cross-endian moves usually require logical or GoldenGate.
- Use OCI Database Migration service when you want an OCI-managed workflow for homogeneous or heterogeneous migrations.
- For applications, separate stateless tiers from stateful ones. Rehost stateless tiers first; replatform to OKE or autonomous services only with tested changes.
- Validate performance with real workload tests, not just row counts.
- Keep source and target in sync until cutover, and prove rollback.
Worked example
A 2 TB Oracle database must move with under two hours of downtime. A junior plan uses Data Pump export/import because it is familiar. That fails the RTO: a 2 TB export/import plus index rebuild can exceed the window. The better plan uses ZDM online physical migration with Data Guard: create a standby in OCI, let it catch up, run a validated switchover during the window, and keep the old primary as rollback. If the source is cross-endian, choose GoldenGate or logical ZDM instead. The reasoning is RTO and platform compatibility first, tool familiarity second.
Traps
- Choosing Data Pump for a tight downtime window.
- Forgetting character-set and version compatibility.
- Testing migration speed but not application performance.
- Cutting over without a sync-validation query or rollback plan.