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

DescriptionSAP Web AS Programming Option
• This system option consists of the J2EE engine only and auxiliary services.
There is no ABAP engine installed.
• The J2EE JAVA engine requires it's own database schema. Therefore a
database instance installation is mandatory.
SAP Web AS JAVA
The following sections detail each step in greater detail.
About SAP Components
The following terms are used to describe the components of an SAP system.
NOTE: Refer to the SAP Web Application Server in Switchover Environments manual for additional
information. Go to http://service.sap.com for this and other SAP documentation.
Table 2-3 SAP Component Terminology
DefinitionTerm
The whole SAP system consisting of one or more SAP instances and a database instance. These
can either be the SAP Web AS ABAP, SAP Web AS JAVA Add-In, or the SAP Web AS JAVA variant.
SAP System
A SAP instance could be for example: a ABAP CI instance, a JAVA CI instance, a SCS instance,
or a DI instance to name a few.
SAP instance
A Database Instance: is a database that supports the SAP Web AS ABAP, SAP Web AS JAVA
scenario, or the SAP Web AS JAVA Add-in scenario. Supported databases with SGeSAP/LX are
MaxDB and Oracle.
DB instance
An ABAP Central Instance provides SAP services for the SAP Web AS ABAP or the SAP Web AS
JAVA Add-in variant. These services consist of SAP work processes such as dialog, update, batch,
spool, gateway, Message Server and the Enqueue Server. It does not include the database processes.
NOTE: With newer versions of SAP the Message Server and the Enqueue Server are separated
from the Central Instance. These two services are now grouped within the SAP Central Services
Instance (ASCS).
ABAP CI
A JAVA Central instance provides server processes for the SAP Web AS JAVA and SAP Web AS
JAVA Add-In variant. These processes include the JAVA dispatcher, JAVA server processes, and the
Software Delivery Manager (SDM). It does not include the database processes.
NOTE: The JAVA CI does not include the Message Server or the Enqueue Server processes. These
two services are grouped within the SAP Central Services Instance (SCS).
JAVA CI
ABAP SAP Central Services. With newer version of SAP the Message Server and the Enqueue Server
have been separated from the APAB CI and grouped into a standalone service described as ABAP
SAP Central Services instance (ASCS).
ASCS
JAVA SAP Central Services. In newer SAP Web AS JAVA variants the Message Server and the
Enqueue Server are implemented as services within the SAP System Central Services Instance (SCS)
and are separated from the JAVA Central Instance (CI) in this way.
NOTE: The name SCS is slightly misleading as it used for the JAVA SAP Central Services.
SCS
Dialog Instance or sometimes called Application Server is a SAP instance, without the DB instance,
consisting of a dispatcher process and dialog work processes. A dialog instance does not contain
the system-critical enqueue and message service components.
D
A JAVA Dialog Instance provides server processes for the SAP Web AS JAVA variant. These processes
include the JAVA dispatcher, JAVA server processes, and newer SAP versions can include the
optional Software Delivery Manager (SDM).
JD
ABAP Enqueue Replication Server. In a high-availability environment the Enqueue Server components
consists of the Standalone Enqueue Server and an Enqueue Replication Server (ERS). The Enqueue
Replication Server (AREP) runs on another host and contains a replica of the lock table (replication
table). If the standalone Enqueue Server fails, the Enqueue Server must be restarted on the host on
which the replication server is running, since this host contains the replication table in a shared
memory segment. The restarted Enqueue Server needs this shared memory segment to generate the
new lock table. Afterwards this shared memory segment is deleted.
Note: The modern SAP terminology for both REP and AREP is Enqueue Replication Service (ERS).
AREP
JAVA Enqueue Replication Server. Provides same functionality as the ABAP Enqueue Replication
Server but for the replication of the JAVA Enqueue Server.
REP
30 Planning a File System Layout for SAP in a Serviceguard/LX Cluster Environment