Managing Serviceguard Extension for SAP on Linux (IA64 Integrity and x86_64), April 2009

DefinitionTerm
A liveCache instance. SAP liveCache technology is an enhancement of the MaxDB database system
and was developed to manage logistical solutions such as SAP SCM/APO (Supply Chain
Management / Advanced Planning Optimizer). In contrast to MaxDB and for performance reasons
the database system is located in the main memory instead of being file system based.
liveCache
Figure 2-1 Comparison between Traditional SAP Architecture and SAP WEB AS Architecture
NOTE: With SAP NetWeaver 04 JAVA, the Message Server and the Enqueue Server are separated from
the central instance. These two services are grouped within the SAP SCS (SAP Central Services) Instance as
services. From NW04s the ABAP SCS can be also separated from the central instance.
Each stack, ABAP and JAVA, has its own Message Service and Enqueue Service. For ABAP systems the SAP
Central Services are referred to as ASCS, for JAVA systems the SAP Central Services are referred to as SCS.
The ASCS and the SCS are leveled as SPOF (Single Point of Failure) and require a high availability setup
therefore. If the ASCS is integrated within the ABAP central instance (standard in NetWeaver 04) the central
instance of the ABAP system also needs a high availability setup.
About Impacted File Systems
In an SAP environment, the storage, the file system layout and the mount points of the SAP system and the
Database instance are key for configuring a Serviceguard cluster.
The file systems are key because of the separation task of the file systems required: which file systems can
be shared between cluster nodes and which file systems cannot. This requires some understanding of how
the file systems are used within an SAP configuration. It is important to describe the application itself, the
environment it runs in and its components. These could be: processes, IP addresses, storage, file systems,
mount points and configuration profiles.
About Impacted File Systems 31