Installing SAP primary and additional application server instances

You can usually achieve redundancy for SAP application servers by installing more than one application server instance, which is supported by the SAP NetWeaver architecture.

From a high availability point of view, it is sufficient to install an application server that uses the physical host name. However, the SAP installer supports installation of an application server instance with its own virtual host name. Exploiting this feature makes it easier to move an instance from one physical machine to another in case this should be necessary, for example, when you migrate to newer and faster hardware. When installing SAP application servers using virtual host names, you should use these virtual host names in the client affinity definition in db2dsdriver.cfg as well.

To get the flexibility provided by SAP's virtualization option, it is recommended that you install every application server with its own virtual host name, provided that the home directory of the <sid>adm is local on each machine.