High Availability + Disaster Recovery (3 Node HADR) has been a hot topic since HA/DR (2 Node) was released for customers back in September 2016. I am exited to announce that it is finally here and available for SAP ASE customers running SAP ASE 16.0 SP03 PL03 and above.
This solution is meant to provide a Disaster Recovery solution on top of High Availability solution. This means, the customers who currenty are running High Availability with SAP ASE on Business Suite (Synchronous Replication) will be able to add a 3rd node as a Disaster Recovery (Asynchronous Replication) node.
A 3 node HA+DR solution consists of 2 High Available nodes and a 3rd node that setup in a remote location for disaster recovery scenarios. The HA pair can be managed by Fault Manager to manage any failover between node 1 and node 2.
Key points to note for this scenario:
- No re-setup required for your current HA pair. This means, no downtime required for your High Availabiltiy pair.
- DR Node can be removed from the setup without affecting the current High Availabiltiy setup.
- Replication between Primary and Standby Host should be configured for synchronous replication.
- Failover only possible between Primary and Standby. The 3rd node cannot be used as a primary node (unless you break replication and manually redirect your application to use the 3rd Node.
- Replication to 3rd node (DR Standby) is asynchronous to avoid any performance impact due to high latency between Data Centers.
- Replication path requires the standby Replication Server to be active.
- Primary, Standby and DR Standby must have the same:
- Operating system and its patch levels
- SAP ASE version
- ASE Configuration
- ASE Logins / Passwords
- Character Set
- Sort Order
If you are unfamiliar with the current 2 node solution, check out my blog from back in 2016. The 2 node HA/DR setup looks as follows:
After we add the 3rd node to the architecture it will look like as follows:
As mentioned above, failover can only happen between the parimary and standby hosts. The setup will look like as follows after failover:
HADR User Guide for SAP ASE SP03 PL03 can be found here.
Guide to add a DR Node to a currently running High Availbility Setup on SAP ASE 16.0 SP02 PL03
can be found here.