Setting Up High Availability for SAP Web Dispatcher on Linux in Azure: Active/Passive and Active/Active Configurations Explained

Learn how to set up high availability for SAP Web Dispatcher on Linux in Azure with detailed guidance on active/passive and active/active configurations. This blog covers architecture, deployment steps, and best practices using SUSE or Red Hat Linux, Azure Load Balancer, and pacemaker clusters for seamless SAP traffic load balancing. Unique :

Setting Up SAP Web Dispatcher High Availability on Linux with Azure

If you’re running SAP applications on Azure, ensuring high availability (HA) for SAP Web Dispatcher is crucial. This component acts as a reverse proxy, balancing HTTP(s) traffic across SAP application servers. Microsoft and SAP experts have outlined detailed steps to deploy SAP Web Dispatcher HA on Linux VMs in Azure, supporting both SUSE and Red Hat Enterprise Linux.

What’s New: Active/Passive and Active/Active HA Options

Two primary HA architectures are available for SAP Web Dispatcher on Azure:

Active/Passive Setup: Uses a Linux pacemaker cluster with a virtual IP managed by Azure Load Balancer. One node handles traffic while the other stands by for failover.
Active/Active Setup: Runs multiple SAP Web Dispatcher instances across different VMs, distributing traffic via Azure Load Balancer.

The blog focuses mainly on the active/passive method, leveraging Linux pacemaker clusters for seamless failover. This approach ensures minimal downtime and automatic error detection.

“Linux pacemaker cluster will continuously monitor the SAP Web Dispatcher active node and services running on it.”

Major Updates: Detailed Deployment Steps and Best Practices

Deploying HA SAP Web Dispatcher involves several critical components:

Two SAP-certified Azure VMs running SUSE or Red Hat Linux, preferably across Availability Zones for better SLA.
Azure Fileshare (Premium) for shared NFS storage, mounted on both VMs.
Azure Load Balancer configured with virtual IP and hostname.
Pacemaker cluster setup for managing failover and resource monitoring.

Key configuration steps include setting up the pacemaker cluster, configuring the Azure Load Balancer health probe, and mounting NFS shares for SAP Web Dispatcher files. Notably, disabling TCP timestamps on VMs behind Azure Load Balancer is essential to prevent health probe failures.

“Complete automation of error detection and start/stop functionality of SAP Web Dispatcher ensures less challenging SLA management.”

Technical Highlights

Pacemaker fencing ensures the active node is fenced off on failure, activating the standby node automatically.
Use Azure Load Balancer with health probes on port 62320 to route traffic only to active nodes.
Mount Azure Files shares with NFS v4.1 for ‘sapmnt’ and SAP Web Dispatcher instance directories.
Configure virtual hostname resolution via DNS or /etc/hosts on both nodes.

What You Need to Know

Before starting, check SAP Notes for certified VM SKUs, supported OS versions, and SAP Web Dispatcher versions. The setup requires careful coordination between Azure infrastructure and Linux cluster management tools.

Also, remember that deploying VMs across Availability Zones boosts uptime, complementing Azure’s 99.99% VM SLA. The blog provides links to official Microsoft and SAP documentation for SUSE and Red Hat setups, ensuring you follow best practices.

Final Thoughts

Setting up SAP Web Dispatcher HA on Linux in Azure is complex but rewarding. This architecture guarantees uninterrupted SAP web traffic handling with automated failover. Whether you choose active/passive or active/active, leveraging Azure’s cloud capabilities combined with Linux pacemaker clusters delivers robust SAP performance.

For tech-savvy SAP admins and cloud engineers, this guide is a must-read to optimize SAP environments on Azure.

Active/passive HA uses Linux pacemaker clusters with virtual IPs for failover management.

Active/active HA deploys multiple SAP Web Dispatcher instances across Azure VMs for traffic distribution.

Azure Fileshare (Premium) supports shared NFS mounts for SAP Web Dispatcher instance filesystems.

Pacemaker automates error detection and failover, ensuring continuous SAP Web Dispatcher availability.

Configuration includes disabling TCP timestamps to ensure Azure Load Balancer health probes function correctly.

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