Migration, Hybrid, and Architecture Best Practices
What to know
Migration and hybrid questions test tool selection and topology. For data movement: OCI Data Transfer service (disk appliance or device) for very large offline moves, FastConnect or site-to-site VPN for ongoing connectivity, rsync-style tools for file and object copies, and Database Migration Service or Zero Downtime Migration for databases. For workloads, Oracle Cloud Migrations discovers and plans, and image import handles custom VM images.
Hybrid design covers DRG with FastConnect and IPSec VPN, transit routing for many VCNs, hybrid DNS with resolver endpoints and forwarding rules, and identity federation to on-premises directories.
Architecture best practices map to the Well-Architected pillars: security and compliance, reliability, performance, cost optimization, and operational excellence. Reliability means regional subnets, multiple availability domains, fault-domain spread, and a deliberate DR strategy - backup and restore, pilot light, warm standby, or active-active.
Traps
- Using a VPN for a sustained high-bandwidth link that FastConnect should carry.
- Designing a single-AD deployment and calling it highly available - one AD failure takes it down.
- Forgetting that a DR plan needs tested runbooks, not just replicated storage.
- Choosing an online transfer when the dataset is too large for the available link.
Rule of thumb
Pick the mechanism by data volume and acceptable downtime: if the link would take longer than the maintenance window, use a Data Transfer appliance; if database downtime must be near zero, use Zero Dataloss Migration approaches such as Zero Downtime Migration. Then layer HA (multi-AD) and DR (cross-region) as separate decisions.