Migration Phases
Phase 1: Prepare
MMC
MMC to enable on-premise database for DG configuration. The steps will be provided as an annexure to this document
MMC to provide a full backup of the database including spfile and control files. This can either be uploaded to azure blob storage or a "jumpbox" server on Azure.
Tessell
Provision an Tessell Oracle HA Service ( 2 DB Nodes + 1 Observer Node) on Tessell
side as per the compute and storage requirements of on-premise database.
Disable the Observer and disable the DG Configuration between these two nodes
Restore the backup provided by MMC on both the nodes on Tessell side
Perform DG configuration to setup the two nodes as DR from the on-premise database
Phase 2: Cutover primary to Tessell
This phase can start anytime once the DG Config between on-premise and Tessell Service is at near zero lag.
Shutdown the applications on the MMC side.
Make sure the lag between on-premise and Tessell HA nodes is 0.
Perform a switchover to make one of the nodes on Tessell Oracle HA Service as primary.
Provide the Tessell service connection string to applications and reconfigure the applications.
Convert the replication between Tessell nodes to be “Sync” mode. (MAX_AVAILABILITY)
Configure the observer on Tessell side to perform failover only between 2 nodes on Tessell side.
Validate that the on-premise database is able to get data from Tessell Oracle HA service.
Validate the applications
Downtime ends
If the new primary environment (app and database) do not perform as expected, perform a failback to on-premise database as primary and reconfigure the connection string back to on-premise database in applications.
Phase 3: Update DGConfig to remove on-premise database(10-15 days after Phase 2)
This phase is to delete the on-premise database after applications are running smoothly with Tessell Oracle HA Service.
Remove the on-premise database from the DG config
Optionally, delete the on-premise database
