To install the (A)SCS instance (standalone enqueue server and message server), use installation program SAPinst. For more information see the SAP Service Marketplace under http://service.sap.com/instguides in the installation guide: Here you choose your operating system, your database, and the installation option (ABAP only, ABAP+Java, Java only).
ABAP only: Für den AS ABAP wird standardmäßig eine ASCS-Instanz (ABAP Central Services) installiert, die den Standalone-Enqueue-Server und den Message-Server enthält.
Java only: With AS Java an SCS instance is installed by default.
ABAP+Java: With AS Java an SCS instance is installed by default (SAP Central Services). With AS ABAP an ASCS instance is installed by default.
You can also later change the configuration of a classical ABAP central system (with enqueue work process) into a system with an ASCS instance. You use the software provisioning manager 1.0 (see SAP Note 1680045 ).
IBM DB2 for z/OS
You can also later change the configuration of a classical ABAP central system (with enqueue work process) into a system with an ASCS instance. The procedure is described in 821904 .
If you want your system to be a high availability solution, you also have to install and configure the replication server. You also use SAPinst for this. You can find the description in the installation guide mentioned above.
After you have installed the replication server, you should carry out some tests to ensure that it is running correctly.
The procedure for UNIX platforms is described in the section, Replication Server: Check Installation. For Windows you can find the post-installation checks in the installation guide.
Depending on your HA solution there are configuration options that are not selected automatically during installation.
More information: Configuring the Replication Server
If the enqueue server and the replication server are running on the same host, a problem may arise if they are shut down normally and restarted.
The shutdown and restart must occur in the correct order.
Stop the enqueue server
Stop the replication server
This ensures that the enqueue server does not receive any more requests if the replication server is no longer running, and therefore no requests can get lost.
Start replication server
Start enqueue server
This ensures that the replication server deletes its old replica first (that is, it cleans up its shared memory), and therefore unwanted replications are avoided.
The problem only occurs on Unix/Linux, since here the shared memory still exists after the processes belonging to it have finished.