How To Minimize Risks when Deploying Linux

Thanks to advances in the latest Linux kernel’s reliability, scalability, and robustness, it became ‘ready for the enterprise data center’ with mission-critical applications. The momentum behind the development and acceptance of Linux in the SAP arena is clear. For example, SAP now relies on Linux for their primary development platforms. Furthermore, the market continues to see stronger offerings from Linux development and services firms such as Novell SUSE and Red Hat. Making Linux part of an SAP environment still requires attention to critical details. It is highly dangerous to leave the business exposed to certain risks. Consequently, anyone taking on the challenge of entering the world of open source and Linux should bear in mind some recommendations that help to minimize risks while getting started.
The complexity of SAP environments increases as companies customize their SAP applications. Customization can negatively affect performance if they don’t also accurately tune their hardware platforms. Each customization influences the SAP solution. Insufficient customization, for example, may result in high input/output loads for a storage system, which affects the overall performance. Introducing Linux into an SAP environment constitutes yet another risk of inadvertently impeding the performance of SAP applications. That’s why Unisys recommends having Linux-based SAP solutions thoroughly analyzed and tuned before going into production. A full system analysis should include measurement of the SAP database, applications, and Web servers as well as the network bandwidth and capacity, disk storage and tape backup utilization. This can potentially save time and money in the long run by identifying obvious and hidden performance problems at an early stage.

Measure and analyze

Every SAP environment has different types of users, different types of data, and different types of applications. In addition, most companies also have various types of hardware from different vendors, which complicates “finger-pointing” during investigations by support staff. Server performance may also vary. This eclectic combination of factors is another reason to recommend measuring the workload mix before and after deployment of any Linux-based SAP applications. The SAP workload can be measured in several different ways. For example, it is possible to start by using Unisys Application Asset Manager (AAM) to discover the existing IT infrastructure and explore the current SAP landscape. This tool collects important data about the operating system(s), database(s), hardware, storage, and SAP applications. The next step is to collect data about the SAP infrastructure with a performance monitor collection tool. This will provide a more granular view of processor and memory utilization levels and input/output performance data from an existing SAP environment, and give an indication of how introducing Linux could affect the system as a whole. Finally, the Unisys Model-Based Transformation (MBT) tool helps to create a graphical overview of the extant IT environment prior to deploying Linux, and a view of the future status once Linux is deployed. MBT generates a Web-based view of the systems landscape taken from the collected performance data and shows if there are unused resources or maximum loads on a server.
What does it take to correctly size Linux-based SAP platforms? For starters, it takes experience in designing and implementing large-scale SAP solutions. An oversized system means a waste of resources. Undersizing a system may result in slow response times. It is advisable to consider taking advantage of services that will help to accurately size and configure a new Linux-based SAP infrastructure from all angles, including servers, disk storage, tape systems, and critical network components. Precision and accuracy are essential to the successful deployment of SAP on Linux.

Seek knowledgeable partners

This tip may sound obvious, but the user should not underestimate the long-term value of working with an outside partner who is fully focused on helping companies to achieve their Linux integration goals. Before building a Linux-based SAP solution, the consulting services of an SAP-certified partner assist with the review of current and future SAP requirements. Working with a partner can also provide access to valuable internal SAP testing and benchmarking opportunities. Since different levels of user demand require specific sizing and configurations, it is helpful to start by defining the specific user base, including real business processes, databases, reports, and customer demands. Several SAP sizing tools are available to measure and precisely calculate the processing requirements. Finding a partner who actually listens to what is required will not only help to accurately plan and integrate Linux. This partner can also help with designing a solution that anticipates future changes, such as acquisitions, new applications, or new users. A knowledgeable partner can also help to design a comprehensive solution which includes items that are often overlooked, such as business continuance or disaster recovery planning.
It is helpful to have all the software components of an SAP environment installed and configured on the hardware platform before it is delivered. Such preparations enable servers to go into production within hours of arrival.
‘Hot stage’ services provide the confidence that the new Linux-based infrastructure has been precisely configured for a customer-specific SAP environment including operating system, SAP installation and server tuning according to the customer’s system environment. A complete hot stage service should subject all systems to numerous tests and customized tuning steps. For example, Unisys offers hot-staged Linux servers for SAP that are quality checked according to 28 different benchmarks in order to ensure accurate performance before they are delivered. Furthermore, each hot-staged Linux server from Unisys is backed by a performance guarantee. A hot-staged SAP solution is the foundation for reducing risks and having peace of mind during Linux deployment.

Comprehensive testing

When it comes to SAP operations, a company should never cut corners. After all, SAP is usually one of the most important applications – if not the most important – in a commercial data center. If the system is down or not performing properly, it could affect revenue and the business as a whole. It is advisable to make sure that the new Linux-based servers are thoroughly tested for reliability with network redundancy testing, including cluster testing for disaster recovery and log shipping, which provides server redundancy (at a remote location) to protect against file corruption while maintaining excellent response times. The responsible systems administration section should also have the results of pre-production testing documented for future reference.
Thorough qualification testing should examine the following aspects of any Linux-based SAP environment: Input/output testing ensures that supported adapters function correctly on the Linux release and that a hardware platform is heavily taxed using a large number of adapters with a heavy input/output load (through both HBA and Ethernet adapters). Processor testing takes the form of tests with various numbers of processors, from one up to the maximum number of processors the system can support. This should include testing hyper-threading technology. Memory testing involves tests with various levels of memory, from the minimum right up to the maximum amount of memory supported by the system. Stability testing is the last step before releasing any major or lesser Linux operating system update. A final stability test should be carried out with all the test tools running concurrently at high load for a minimum of 72 hours. Test tools are SPECint2000, SPECfp2000, SPECint_rate2000 and SPECfp_rate2000. In addition, Unisys makes extensive use of the Unisys Test Suite and the certification suites of Linux distributors.
Minimizing risks in an SAP Linux environment takes more than a quick, inaccurate sizer. Professional consultants help customers to build a configuration that fits the requirements. Infrastructure consulting helps implement the SAP software and figure out problems that have to be remedied. The hot staging system ensures that there will be no problems later on. Additional migration capabilities help the migration process, for example adding a Linux server as an application server in a Unix environment.

Thomas Kohlgraf
Thomas Kohlgraf