What is SID in SAP

Creation of a highly available SAP NetWeaver Multi-SID configuration

  • 7 minutes to read

In September 2016, Microsoft released a feature that allows you to manage multiple virtual IP addresses using an Azure internal load balancer. This functionality already exists in the Azure external load balancer.

If you have a SAP deployment, you can use an internal load balancer to create a Windows cluster configuration for the SAP ASCS / SCS instance as outlined in the SAP NetWeaver High Availability Guide on Windows Virtual Machines.

This article covers the transition from a single ASCS / SCS installation to a SAP Multi-SID configuration by installing additional SAP ASCS / SCS cluster instances on an existing Windows Server Failover Clustering (WSFC). When this process is complete, you have configured a SAP Multi-SID cluster.

requirements

You have already configured a WSFC cluster to be used for a SAP ASCS / SCS instance as described in the manual on "High Availability" of SAP NetWeaver on Windows Virtual Machines and shown in this diagram.

Target architecture

The goal is to install multiple SAP ABAP ASCS or SAP Java SCS cluster instances on the same WSFC cluster, as shown here:

Note

There is a limit to the number of private front-end IPs for each Azure internal load balancer.

This means that the maximum number of SAP ASCS / SCS instances on a WSFC cluster is equal to the maximum number of private front-end IPs per Azure internal load balancer.

For more information about load balancer limits, see the "Front-end private IP per load balancer" section in Network limits: Azure Resource Manager.

The complete scene with two highly available SAP systems then looks like this:

Important

The setup must meet the following conditions:

  • The SAP ASCS / SCS instances must share the same WSFC cluster.
  • Each DBMS SID must have its own dedicated WSFC cluster.
  • SAP application servers that belong to the same SAP system SID must have their own dedicated VMs.

Prepare the infrastructure

To prepare your infrastructure, you can install an additional SAP ASCS / SCS instance with the following parameters:

Parameter namevalue
SAP ASCS / SCS-SIDpr1-lb-ascs
Internal load balancer for the SAP DBMSPR5
Name of the SAP virtual hostpr5-sap-cl
IP address of the SAP ASCS / SCS virtual host (additional IP address for Azure load balancing)10.0.0.50
SAP ASCS / SCS instance number50
ILB test port for the additional SAP ASCS / SCS instance62350

Note

With SAP ASCS / SCS cluster instances, a unique test port is required for each IP address. For example, if an IP address of an Azure internal load balancer is using test port 62300, no other IP addresses on the load balancer can use test port 62300.

For our purposes we use test port 62350, since test port 62300 is already reserved.

You can install an additional SAP ASCS / SCS instance on the existing WSFC cluster with two nodes:

Virtual machine roleVirtual machine host nameStatic IP address
1. Cluster node for ASCS / SCS instancepr1-ascs-010.0.0.10
2. Cluster node for ASCS / SCS instancepr1-ascs-110.0.0.9

Create a virtual host name for the SAP ASCS / SCS cluster instance on the DNS server

You can create a DNS entry for the virtual host name of the ASCS / SCS instance with the following parameters:

New SAP ASCS / SCS virtual host nameAssigned IP address
pr5-sap-cl10.0.0.50

The new host name and new IP address are displayed in the DNS manager, as can be seen in the following screenshot:

The procedure for creating a DNS entry is also described in detail in the main manual on the topic of "High Availability" of SAP NetWeaver on Windows virtual machines.

Note

The new IP address that you assign to the virtual host name of the additional ASCS / SCS instance must be the same as the new IP address that you assigned to the SAP Azure load balancer.

In this scenario, the IP address is 10.0.0.50.

Add an IP address to an existing Azure internal load balancer using PowerShell

To create multiple SAP ASCS / SCS instances on the same WSFC cluster, use PowerShell to add an IP address to an existing Azure internal load balancer. Each IP address requires its own load balancing rules, test port, front-end pool, and back-end pool.

The following script adds a new IP address to an existing load balancer. Update the PowerShell variables for your environment. The script creates all the necessary load balancing rules for all SAP ASCS / SCS ports.

After running the script, the results will be shown in the Azure portal as shown in the following screenshot:

Adding disks to cluster computers and configuring the SIOS cluster shared disk

You need to add a new shared cluster disk for each additional SAP ASCS / SCS instance. The SIOS DataKeeper software solution is currently used as the common WSFC cluster data carrier for Windows Server 2012 R2.

Follow these steps:

  1. Add another disk or disks of the same size (as a striped set) to each of the cluster nodes and format them.
  2. Configure storage replication with SIOS DataKeeper.

This procedure assumes that you have already installed SIOS DataKeeper on the WSFC cluster computers. If you have this installed, you must now configure replication between the computers. The procedure is described in detail in the main manual on "High Availability" of SAP NetWeaver on Windows virtual computers.

Provision of virtual machines for SAP application servers and DBMS clusters

To complete the preparation of the infrastructure for the second SAP system, you must do the following:

  1. Deploy dedicated VMs for SAP application servers and place them in their own dedicated availability group.
  2. Deploy dedicated VMs for DBMS clusters and place them in their own dedicated availability group.

Install the second SAP SID2 NetWeaver system

The complete process of installing a second SAP SID2 system is described in the main manual on the subject of "High Availability" of SAP NetWeaver on Windows virtual machines.

The general procedure is as follows:

  1. Install the first SAP cluster node
    In this step you install SAP with a highly available ASCS / SCS instance on the EXISTING WSFC cluster nodes 1.

  2. Change the SAP profile of the ASCS / SCS instance

  3. Configure a test port
    In this step, you configure a SAP cluster resource SAP-SID2-IP-Testport using PowerShell. Perform this configuration on one of the SAP ASCS / SCS cluster nodes.

  4. [Install the database instance] [sap-ha-guide-9.2].
    In this step, you install DBMS on a dedicated WSFC cluster.

  5. [Install the second cluster node] [sap-ha-guide-9.3].
    In this step, you install SAP with a highly available ASCS / SCS instance on the existing WSFC cluster node 2.

  6. Open Windows firewall ports for the SAP ASCS / SCS instance and the test port.
    On both cluster nodes that are used for the SAP ASCS / SCS instances, open all Windows firewall ports that are used by SAP ASCS / SCS. These ports are listed in the main manual on "High Availability" of SAP NetWeaver on Windows Virtual Machines.
    Also open the test port for the Azure internal load balancer, in our scenario 62350.

  7. Change the start type of the Windows service instance for SAP ERS

  8. Install the primary SAP application server on the new dedicated virtual machine

  9. Install the additional SAP application server on the new dedicated virtual machine

  10. Testing the failover of the SAP ASCS / SCS instance and the SIOS replication

Next Steps