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Guest Blog by : Sivakumar Varadananjayan, Cognizant

How to maximize your SAP System availability with SUSE.

Lets have a closer look at the design and simplified architecture of a high available SAP system.

Criticality of SAP System availability

As per Analyst observation, Enterprise customer’s unplanned system downtime per hour will cause few hundred thousand to millions of dollars loss based on the customer’s business value. This can vary for each customer and each industry. Just imagine a Retail customer’s loss if an unplanned system downtime happens during Thanksgiving week or Christmas or New Year week. This kind of loss is applicable for all industry customers and the actual loss varies from case to case.

It clearly shows the importance of designing and implementing maximum system availability for Enterprise applications. This is very critical and almost mandatory. As more Enterprise applications are moving to Cloud, the design needs to consider Cloud compatible High Availability solutions for these applications.

Let us see the critical design aspects for SAP S/4HANA systems with High Availability and Disaster Recovery on Cloud.

SAP S/4HANA High Availability Design

S/4HANA Architecture design needs to be fine-tuned based on the customer’s requirement on system availability i.e 99.99% or 99.95% or 99.9% . The following steps need to be followed during the SAP S/4HANA Architecture design.

  • Identify the SPOF (Single Point of Failure) components / services
  • All Applications / Services SPOF need to be in a High Availability cluster
  • All infrastructure SPOF components need to have redundancy

Here’s a list of key services / layers that comprise a S/4HANA implementation on Public Cloud:

  • SAP Central Services
  • Database layer – SAP HANA
  • PAS layer
  • NFS layer

The following services / layers are potential SPOF:

  • SAP Central Services
  • Database layer – SAP HANA
  • NFS layer

Eliminate Single Point of Failure (SPOF)

To eliminate SPOF for S/4HANA systems on Cloud, we need to focus on the following aspects:

  1. High Availability Cluster implementation of services for automated failover from one node to another in case of a node failure
  2. Data Replication between nodes configured in a High Availability cluster.

High Availability Clustering

You can use the SUSE Linux Enterprise High Availability Extension* to configure the following components in a High Availability cluster to ensure maximum system availability.

  • SAP Central Cervices:

    • You need at least 2 VMs (Virtual Machines) to configure an ASCS/ERS high availability cluster.
    • You can configure the ASCS/ERS cluster in either ENSA 1 or ENSA 2 architecture
    • You can also configure a multi-SID ASCS/ERS cluster with upto 5 SAP SIDs on the same cluster. This would require at least 3 VMs.
  • S/4HANA Database layer:

    • You need at least 2 VMs (Virtual Machines) to configure SAP HANA HA/DR cluster in a scale-up deployment
    • The SUSE High Availability cluster is used to detect system failures and facilitate automatic failover
  • NFS (Network File Systems):

    • You need at least 2 VMs (Virtual Machines) to configure highly available clustered Network File Shares (NFS) servers

Data Replication

  • SAP Central Cervices:
    • ASCS/ERS clusters use a highly available clustered Network File Shares (NFS) service. So they do not need any Data Replication.
  • S/4HANA Database layer:
    • HANA System Replication (HSR) is used to replicate contents between primary and secondary HANA systems. This is also SAP’s recommended approach.
  • NFS (Network File Systems):
    • Distributed Replication Block Device (DRBD) is used to replicate data between the clustered NFS Server nodes.

In Summary:
SUSE Linux Enterprise High Availability Extension. An industry-leading open source high availability clustering system designed to virtually eliminate unplanned downtime, be easy to use and be deployed in both physical and virtual environments. This helps you maintain business continuity and minimize unplanned downtime.

Do you know that SUSE Linux Enterprise Server for SAP Applications is the leading Linux platform for SAP HANA, SAP Net Weaver and SAP S/4HANA solutions enabling reduced risk from service outages, less time and effort for system maintenance, and faster services deployment on premise and in the cloud.

The next part of this series will bring you more information on SUSE Linux Enterprise Server for SAP, how to avoid unplanned downtime with SUSE Linux Enterprise Live Patching, SUSE Manager and more. Stay tuned!

Check out the flyer to learn more!

 

 

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