Two-Node Cluster With One Logical Host, Application Servers, and Separate NFS Cluster

You can also place SAP application servers on one or both physical hosts. In this configuration, you must provide NFS services from a host outside the cluster. Set up the application servers to NFS-mount the file systems from the external NFS cluster, as illustrated in Figure 1-3. In case of failover, the logical host containing the central system (the central instance and database instance) switches to the backup node. The application servers do not migrate with the logical host, but are instead started or shut down depending on where the logical host is mastered. This prevents the application servers from competing for resources with the central instance and database.

Figure 1-3 Asymmetric SAP Configuration With Application Servers and External HA-NFS