CONDICIONES DE LAS NIÑAS Y LOS NIÑOS QUE VIVEN CON SUS MADRES

For the installation procedure you have to understand the architecture of an SAP system.

An SAP system consists of the components shown in the graphic: One database and one or more instances. The instance that, together with the database, forms a functional SAP system is also known as the central instance. There is not more than one central instance installed for every SAP system. A central system is an SAP system consisting out of only the central instance and the database, running on the same host.

It is possible to install two instances of an SAP system or even of different SAP systems on one host. Before you install two SAP systems (and possibly their databases) on one host, you should examine the extent to which the chosen hardware is capable of handling the anticipated load. Other aspects to be considered are situations such as upgrades or restore scenarios - for example, one SAP system is to be recreated from a backup whilst the other SAP system should continue to be used without interference.

Within a company, no SAP system IDs (SIDs) should be used more than once.

An instance of an SAP system is an administrative unit in which components of an SAP system that provide one or more services are combined. The services within one instance are started or stopped together.

There are three different types of SAP systems:

AS ABAP based - for example SAP ECC or SAP BW AS Java based - for example SAP XSS or SAP Portal

AS ABAP + Java based - only SAP Solution Manager and SAP PI

The (ABAP) dispatcher is the central process of an ABAP instance. This process starts other processes that belong to the instance, such as the gateway (abbreviated as GW in the graphic), the Internet Communication Manager (ICM), and a configured number of work processes.

You configure an ABAP instance using an instance profile. The ABAP instance has shared (main) memory areas and its own directory structure in the file system.

Figure 5: AS ABAP based SAP System

An (ABAP) instance consists of a dispatcher and several work processes. An instance requires a minimum of two dialog work processes. Otherwise it is not possible to start it. Several instances can be installed on the same host. The instances must then have different instance numbers. The instance number is a two-digit number, and is chosen at installation. It defines a range of standard communication ports

for processes of the instance. The standard port of the dispatcher is 32$$ where $$

denotes the instance number. For example 3200 if the instance number 00 was chosen at installation. If several instances are installed on a shared host, these instances use their own, separate, (main) memory areas, and each instance has its own directory structure in the file system.

Hint: You should not use the instance numbers 98 and 99, because they are reserved for the SAProuter.

An SAP system can have several instances. One of them is the central instance. It includes an additional process – the ABAP Message Server – which only exists once across the system. Furthermore, the central instance is the only instance that offers one or more enqueue work processes.

Hint: Note that this definition of the term central instance cannot be used in the sense described when the ABAP Central Services Instance (ASCS) is installed. You will find a description of the ASCS concept in the appendix to this lesson.

An instance is also called an application server. The application server provides the runtime environment for the business applications of an SAP system.

The (Java) dispatcher is the central process of a Java instance. This process distributes the incoming requests to the available server processes.

Figure 6: AS Java based SAP System

A Java instance consists of a Java dispatcher and one or more server process. Several instances can be installed on the same host.

A (Java-based) SAP system can have several instances. One of them is the (Java) central instance. It includes an additional process - the Software Deployment Manager (SDM) - which can only be configured once across the SAP system. There is also a Java Central Services (SCS or CS) instance. This CS instance offers the Java Message Server and the Java Enqueue Server. In the standard installation, the Java central instance and the CS instance are located on the same host.

You can install additional Java instances on the same host together with the central instance or on other separate hosts.

AS ABAP+Java-based instances (dual stack instances) offer ABAP and Java-based processes. This results in the following definition of a central instance: The central instance of an AS ABAP+Java-based SAP system offers all the processes of an ABAP central instance and a Java central instance.

The Java Central Services instance does not belong to the AS ABAP+Java central instance. It is started and stopped separately.

Note: The Java server processes are not the equivalent to the ABAP work processes: the Java server processes distribute the incoming work to underlying so called threads. So the Java server processes are kind of sub-dispatchers.

Note: In future AS Java releases, starting from 7.10, there will be no Java dispatcher any longer. Instead the load balancing is been done by a Java ICM process.

Figure 7: AS ABAP+Java based SAP System

An AS ABAP+Java-based SAP system always provides one ABAP+Java-based central instance. Other instances are also AS ABAP+Java-based.

Caution: Again: avoid installing AS ABAP+Java based (dual stack) systems!

Exceptions: SAP PI and SAP Solution Manager.

Since several releases it is almost not possible to install other dual stack systems any longer . This is because of several problems and high costs related to this architecture.

Hint: In case you are still running a dual stack systems that was installed in former days, there is a possibility to split it up into an AS ABAP and a second AS Java based SAP system.

This can be done using the installation tool SAPinst. In 2011 this should be available for splitting up all types of SAP systems.