My company is preparing for a complete cloud migration from our local VMware environment to Oracle Cloud Infrastructure (OCI). We have a mix of Linux VMs and critical Oracle Database instances. What are the key tools and strategies within OCI to achieve a near zero-downtime transition? Are we better off with a Lift and Shift approach using tools like OCI’s Cloud Migrations Service, or should we look at a Replatforming approach for the database to use Autonomous Database immediately? We are focused on minimizing application downtime.
3 answers
For minimal downtime, the recommended approach is a staged cloud migration. For your Linux VMs, use the OCI Cloud Migrations service for a Lift and Shift. This tool automates the discovery, replication, and launch of your source VMs as OCI Compute instances, minimizing the cutover window. For your critical Oracle Database instances, use Oracle GoldenGate for a near-zero downtime logical migration. GoldenGate enables real-time data replication between your on-premises database and the target OCI Database Cloud Service or even the Autonomous Database. This allows your applications to keep running on-premises until you perform the final, quick switchover to OCI, achieving a true low-downtime transition. Replatforming to Autonomous should be planned post-migration for optimization.
If we use GoldenGate for the Oracle Database to Autonomous Database migration, how do we handle the final application connection string change to point to the new OCI endpoint during the cutover to ensure the low-downtime goal is met?
Start with a Lift and Shift for the VMs using the OCI Cloud Migrations service. For the Oracle Database, employ GoldenGate for real-time replication to your target OCI Database or Autonomous Database to guarantee a near low-downtime cutover during the final cloud migration phase.
Also, don't overlook a crucial part of the cloud migration—the network connectivity itself. Make sure you set up a high-bandwidth, dedicated connection like FastConnect between your on-premises data center and OCI for initial large-scale data transfer and continued hybrid operations.
The best practice here is to utilize a Virtual IP (VIP) or an alias DNS entry for your database connection in the application layer. Instead of embedding the direct connection string, the application points to the VIP/DNS entry. During the final cutover, after stopping application writes to the source, you simply redirect the VIP/DNS entry to the new Autonomous Database endpoint in OCI. This minimizes the application configuration change to just a DNS update, making the actual switchover extremely fast and ensuring the low-downtime objective.