Pacemaker Cluster works with SAP HANA System Replication (SAP HSR).

SUSE developed in collaboration with SAP the SAPHanaSR solution and released it as part of SLES for SAP Applications. This solution is based on Pacemaker Cluster that is automating failovers between two SAP HANA databases that are mirroring each other. This solution was later adopted by RedHat and is now jointly developed by both companies. Therefore, this whole blog is equally applicable to both Operating Systems.

Pacemaker Cluster with SAP HANA System Replication as visualized below is based on two identical servers (VMs) each having one SAP HANA database. Both servers are bundled together by SUSE Pacemaker Cluster.

Pacemaker Cluster for SAP HANA Architecture

SAP HANA database on primary server is replicating information to SAP HANA database running on secondary server. Replication method is based on Synchronous SAP HANA System Replication – this is to ensure that no data is lost during failover. Both databases are running at the same time, however only primary database can support customer workloads. Secondary database is either completely passive or can be active in read-only mode (since SAP HANA 2.0).

Failure of primary SAP HANA database is automatically detected by Pacemaker Cluster. The cluster will automatically shutdown primary database (if still partially running) and will activate secondary database. It will also relocate virtual IP to ensure that all applications using the database can reconnect to new primary SAP HANA database. Since all the data is already pre-loaded in memory of new primary database this failover is very fast.