Double-Stack (ASCS and SCS) high availability setup

This Double-Stack high availability setup is used for Double-Stack SAP solutions.

Figure 1. Double Stack high availability setup
(A)SCS high availability setup
The Double-Stack installation contains all the components of both the ABAP and Java installation. A Double-Stack system has two SAP Central Services instances in parallel: an ABAP SCS and a Java SCS. Each of them works the same way as the ABAP only and Java only setups. During the failover, the corresponding two virtual IP addresses for the ASCS and SCS are moved to the failover node as well.
Primary and Additional AS node
A Double-Stack Application Server comprises one SAP instance that runs an ABAP and a Java Application Server in parallel. Within a System Automation for Multiplatforms domain, the Double Stack Application Server instance is automated as two Application Server resources. The StartAfter relationship is defined between the Java Application Server and the ABAP Application Server. This StartAfter relationship causes that starting the Java Application Server automatically triggers the prior start of the ABAP Application Server.
Web Dispatcher and SAProuter node (optional)
The Web Dispatcher and SAP router high availability setups consist of at least two nodes, which run the Web Dispatcher and SAP Router instances in a failover setup. Both components are essential for the clients to access the Application Servers. Therefore, the failover of one instance to standby nodes includes the corresponding virtual IP address as well.
Database high availability setup
The database high availability setup is explained in Database high availability installation setup.
NFS high availability setup
The NFS high availability setup is explained in NFS high-availability installation setup.
Table 1. Double-Stack resources and the corresponding components

Double Stack resources

SAP component

ABAP resource

ABAP SAP Central Services (ASCS) instances use an own virtual host name on two nodes.

Java resources

Java SAP Central Services (SCS) instances use an own virtual host name on two nodes.

ABAP and Java common resources
  • Both Enqueue Replication Servers have their own virtual host name on two nodes.
  • Database server instances use an own virtual host name on two nodes.
  • Primary Application Server for ABAP and Java instance on first node.
  • Additional Application Server for ABAP and Java instances on other nodes.

Independent resources (optional)
  • Host Agent
  • Web Dispatcher instances use an own virtual host name on two nodes.
  • SAProuter setup on two nodes.