Chapter 4. HA Solution for NetWeaver or S/4 Based on ABAP Platform 1709 or older
4.1. Standalone Enqueue Server 1 (ENSA1)
When using the old Standalone Enqueue Server (ENSA1), the ASCS instance has to fail over the cluster node where the active ERS instance is running and it must be ensured that the ERS instance is shut down and moved to the node where the ASCS instance was running when it was online. This is because the ASCS instance has to access the shared memory where the ERS instance maintains a copy of the enqueue lock table to continue to keep track of the enqueue locks of active transactions. ENSA1 is supported in pacemaker as a two-node cluster configuration, mainly because of the restriction that the ASCS instance must “follow” the ERS instance.
4.2. Supported Scenarios
| Supported Scenario | Description |
|---|---|
| Two node cluster | For ENSA1 the ASCS instance must always move to the node where the ERS instance is running |
| ABAP/Java Dual-Stack | Supported by Master/Slave Resources in all RHEL 7.x releases |
4.2.1. ABAP/Java Dual-Stack
ABAP/JAVA Dual-Stack is supported using the Master/Slave methodology, that’s supported in all RHEL 7.x minor releases. Please follow the configuration guide: Configure (A)SCS/ERS SAPInstance cluster resource.
However, since SAP no longer recommends dual-stack setups where both ABAP and JAVA instances share the same SID, it would be better to consider doing a Dual-Stack Split, so that the ABAP and JAVA stack will use separate SIDs. With such a setup you then could use the Standalone approach for managing the ASCS/ERS instances for the ABAP stack and the SCS/ERS instances for the JAVA stack. You need to configure separate resource groups for each instance and set up appropriate constraints based on the separate SIDs for each part of the environment. Please follow configuration guide: Configuring SAP NetWeaver ASCS/ERS ENSA1 with Standalone Resources in RHEL 7.5+ and RHEL 8.
4.3. Support Policies
Please refer to Support Policies for RHEL High Availability Clusters - Management of SAP NetWeaver in a Cluster.
4.4. Configuration Guides
- On-Premise: Configuring HA clusters to manage SAP NetWeaver or SAP S/4HANA Application server instances using the RHEL HA Add-On
- AWS: Configure SAP NetWeaver ASCS/ERS ENSA1 on Amazon Web Services (AWS)
- Azure: Azure Virtual Machines high availability for SAP NetWeaver on Red Hat Enterprise Linux with GlusterFS
- Azure: Azure Virtual Machines high availability for SAP NetWeaver on Red Hat Enterprise Linux with Azure NetApp Files for SAP applications
- Azure: High availability for SAP NetWeaver on Azure VMs on Red Hat Enterprise Linux with NFS on Azure Files
- GCP: HA cluster configuration guide for SAP NetWeaver on RHEL
