Review “Upgrading from a previous version” for steps common to all database migrations.
Synchronize and shutdown multiplex all query nodes. See “Synchronize and shutdown multiplex query nodes”.
Migrate local stores, if necessary. This step is only required if you created local stores for your 12.x multiplex query nodes. See “Migrate your local stores”.
Run sp_iqcheckdb to check the validity of your 12.x databases. Repair any index and allocation problems. See “Verify the 12.x databases before migration”.
Start the multiplex write server in single node mode. See “Start the multiplex write server in single node mode”.
Shut down your 12.x server and back up your database. See “Shutdown your 12.x server”.
Run iqunload with the appropriate parameters to migrate your databases. See “Use iqunload to migrate your database”.
Use the -iqro 1 -iqmpx_sn 1 switches to start the writer in READONLY mode. See “Start the 15.2 migrated database”.
Run sp_iqcheckdb to verify your migrated databases, then backup the databases. See “Verify the migrated databases”.
Synchronize the secondary nodes from the coordinator node. See “Manually synchronize the secondary nodes”.
Start the secondary nodes, then import the schema and data for the local stores into the coordinator. See “Start the secondary nodes”.
Set the failover mode for the failover node. See “Set the failover node”.
Complete any necessary postmigration tasks. See “Postmigration tasks”.
