Migrate to ORS with Redis Cluster

Preparation steps

1. Deploy Redis Cluster and configure it for ORS persistence.
2. Deploy Redis Cluster CPU and memory monitoring tools.
3. Upgrade ORS applications to 8.1.401.10 or higher.
4. Configure all necessary ORS Application options for persistence to Redis, but do not enable it yet (do not set [persistence] type=redis yet).
5. Restart ORS using the standard procedure. That is, you must restart backups, switchover, and restart new backups.
6. Ensure that ORS applications continue to work as expected. Verify that persistence using Cassandra continue to work as expected, if enabled.

Enable Redis persistence

1. Enable Redis persistence by setting [persistence] type= redis for backup applications. Restart backup applications for the new setting to take effect. Trigger a switchover to make them Primary.
2. Verify that Primary ORS applications are now connected and are doing serialization to Redis. After the switchover, ORS sessions which were in progress, will not be restored and routing may be failed for those calls. Verify that new ORS sessions are processed as expected.
3. Monitor Redis Cluster nodes CPU and memory consumption. Add more Redis nodes or upgrade memory capacity depending on the monitoring data. Consult Redis support, if necessary.
4. Enable Redis persistence by setting [persistence] type = redis for backup applications. Restart backup applications for the new setting to take effect. Trigger switchover to make them Primary.
5. Verify that new Primary ORS applications are now connected and are doing serialization to Redis. After switchover, ORS sessions which were in progress, should be restored from Redis. Verify that all calls are processed as expected.

Rollback

If the migration to ORS with Redis is not successful or if the new solution after the migration is not working as expected, do the following steps to rollback:

1. Disable Redis persistence for all ORS applications.
2. Restart ORS using the standard procedure (restart backups, switchover, and restart new backups).
3. Investigate the cause of the issue and resolve it before doing the migration procedure again.

Post migration steps

Remove Cassandra when you are satisfied with the new ORS with Redis Cluster solution.