Disaster Recovery module is enhancing the design by adding protection against Regional disaster. Such disaster events can be caused by nature (floods, tornadoes, hurricanes or earthquakes), by humans (strikes, terrorism) or by technology (power blackout).
All events mentioned above are typically having wide area of impact. Since High Availability design is based on synchronous replication between two Availability Zones of same Region, there are chances that both primary and secondary system will be impacted at the same time by Regional disaster. Therefore, there is need to replicate the data outside the impacted Region.
SAP HANA Asynchronous (ASYNC) Replication is recommended approach how to ship the data to remote Disaster Recovery location (independent Region). The advantage is that Asynchronous Replication Mode is not susceptible to increased latency because the replication is happening on background.
As explained in System Replication Guide: Replication Performance Problems the network bandwidth is still critical even for Asynchronous Replication Mode.
Number of active nodes of the target SAP HANA System in the Disaster Recovery location must be same as on source system (see Administration Guide: General Prerequisites for Configuring SAP HANA System Replication for additional information).
During Disaster Recovery Event both SAP Application Servers and SAP HANA Database is being failed over to Disaster Recovery location. All applications that were subject of failover are reconfigured and tested as part of failover procedure. For all external applications that need connectivity to SAP HANA System it is strongly recommended to connect via DNS, so that application connectivity can be restored by adjusting single DNS entry.
Additional Information:
- System Replication Guide: SAP HANA System Replication
- Administration Guide: SAP HANA System Replication
- Administration Guide: SAP HANA Multitier System Replication
- Administration Guide: SAP HANA Multitarget System Replication
- Administration Guide: Disaster Recovery Scenarios for Multitarget System Replication
- How To SAP HANA System Replication Whitepaper
- SAP Note 2407186: How-To Guides & Whitepapers For SAP HANA High Availability