SGeSAP and HP Somersault

HP Somersault (B8438) is the latest technology to guarantee a failsafe operation of the enqueue server, one of the four SPOF's in an SAP R/3 system. Figure 1-7 “HP Somersault System Environment” shows a sample HP Somersault system environment.

Figure 1-7 HP Somersault System Environment

SAP R/3 supports the usage of HP Somersault for protecting the enqueue server only in complete High Availability scenario with MC/ServiceGuard and SGeSAP eliminating the other SPOFs.

MC/ServiceGuard and SGeSAP protect against the loss of service due to database and message server failure, and HP Somersault protects against Enqueue failure.

The enqueue server is the central process that provides access to the Enqueue lock table in an SAP R/3 system. HP Somersault protects the Enqueue service by introducing the HP Somersault Enqueue process (ensserv) that replaces the standard SAP R/3 Enqueue service. An HP Somersault unit consists of three members:

The primary and secondary members host the HP Somersault enqueue process (enssserv). The witness acts as an arbitrator to the unit in the event of a failure.

HP Somersault Machine Sets

An HP Somersault machine set is a group of machines that have been designated to fulfill a specific HP Somersault role. The two kinds of machine sets that are of interest when integrating HP Somersault with MC/ServiceGuard are:

• Server Set Machines

  The server machine set is stretched over nodes outside the MC/ServiceGuard cluster only. These machines are able to host the primary and secondary members of the HP Somersault unit.

• Witness Set Machines

  The witness machine set consists of the systems that host the witness member of the HP Somersault unit. all machines in the MC/ServiceGuard environment are members of the witness machine set. This means that every cluster node must have the HP Somersault installed and configured.

In an MC/ServiceGuard environment the handling of the HP Somersault unit is transparent to the administrator. HP Somersault starts and stops with the startup and shutdown of the Central Instance out of a MC/ServiceGuard package. Refer to Chapter 3, "Chapter 3 “SGeSAP Administration”," for additional information. For supported configurations and further details on HP Somersault refer to your HP Somersault documentation.