SAP Basis Tech Supports

Symptom

This note contains information about using an SAP system based on SAP NetWeaver Application Server on Windows in a virtualized environment. Furthermore, it describes the virtualization solutions supported by SAP, the configuration requirements, and support restrictions.

Other terms

VMware, VMware ESX Server, VMware GSX Server, Microsoft Virtual Server, Microsoft Hyper-V, Windows Server 2008, XEN, vSphere

Reason and Prerequisites

For more information and FAQs about virtualization of SAP applications on Windows, see:
http://www.sdn.sap.com/irj/sdn/windows-virtualization

Solution

Contents
1 Supported virtualization solutions
2 Supported operating system versions
3 Supported SAP applications
4 Configuration requirements
5 Support restrictions
6 Other virtualization solutions
7 Values based on experience when using virtualization

1 Supported virtualization solutions

SAP supports the following virtualization solutions for productive use of SAP systems on virtualized hardware:
VMware ESX Server 3.x and 4.0 (vSphere)Microsoft Hyper-V
2 Supported operating system versions

SAP supports exclusively Windows 64 bit in a virtualized environment for AMD and Intel processors.

3 Supported SAP applications
All SAP applications that are based on SAP NetWeaver Application Server ABAP or Java and that are supported in a non-virtualized environment are also supported in a virtualized environment.For support information on SAP applications that are not based on SAP NetWeaver Application Server ABAP or Java, contact the person responsible of the relevant SAP application.SAP components, such as TREX or MDW, are very resource-intensive. Information about operating TREX in a virtualized environment is available in Note 1303814, information about MDW is available in Note 1336014.
4 Configuration requirements
For productive SAP systemsAll SAP applications based on SAP kernel 6.40 and higher are supported for productive use as long as you have implemented enhanced monitoring for virtualization. Check the requirements and minimum support package levels mentioned in Note 1409604 for the activation of the enhanced monitoring.For the Java stack, you must reserve the main memory (no memory overcommitment), and have sufficient physical memory available because the garbage collector must be able to access the entire Java heap. Information about the Java VM settings is available in Note 723909.For productive use of the SAP system, you must reserve the resources for the CPU and memory. The behavior of several parallel virtual machines is only predictable if all machines use reserved resources. Otherwise, performance might deteriorate significantly.For non-productive SAP systems
For non-productive use, SAP supports all SAP applications based on SAP kernel 4.6D and higher with the following restrictions:For SAP releases based on SAP kernel 6.40 and higher, you must activate enhanced monitoring for virtualization (see Note 1409604).For SAP releases based on SAP kernel lower than 6.40, enhanced monitoring for virtualization does not exist.
Note the following restrictions for these SAP releases:
Certain SAP services (for example, Early Watch, Going Live) are not available for these releases.
SAP does not provide support for performance problems.SAP allows to perform the upgrade of a 32-bit SAP system in a virtualized environment, if afterwards the SAP system is migrated to Windows 64-bit. The productive use of those 32-bit SAP systems isnotallowed.

5 Support restrictions
For third-party componentsFor third-party components (e.g. Adobe Document Services) that are installed with the SAP system, support restrictions might exist in a virtualized environment. If the third-party software partner ensures only restricted support in a virtualized environment for their product, this restriction also applies to the use of the software in an SAP environment. In this case, SAP must pass the support restriction of the third-party software partner onto the customer.SAP tests its applications on VMware ESX or Hyper-V. The virtualization infrastructure contains additional components for management, high availability, migration, and development. SAP does not perform any checks regarding these components and their compatibility with SAP applications. If problems occur with these infrastructure components, contact VMware or Microsoft directly.On part of the database manufacturer
Together with your hardware partner, you must ensure that the configuration of your virtual environment provides sufficient scope for times with a high workload, because the performance of databases strongly depends on disk I/O, network, and other areas of system performance.
Also check the release and support information provided by your database manufacturer.Support by Oracle
Note 1173954: Support of Oracle for VMware and XEN
Note 1329848: Oracle Support for Windows Server 2008 Hyper-VSupport on MaxDB
Note 1142243: MaxDB release for virtual systemsSupport by Microsoft
For information about the support of a Microsoft product in a virtualized environment, see the Microsoft Knowledge Base article 956893.Support by IBM
For detailed support information about DB2 on VMware or Hyper-V, see Note 1130801.

6 Other virtualization solutions
VMware, GSX Server, VMware workstation, Microsoft Virtual Server
Due to their restriction to 32-bit, single CPU, and host/guest operation, these virtualization products are not suitable for productive SAP systems. However, it might be advisable to use these products to operate non-production systems (demo systems, test systems, development systems, and so on).XEN
This virtualization solution is not supported. XEN is integrated in several Linux distributions and uses a virtual system format compatible with Microsoft Hyper-V. In theory, it is possible to use a Windows guest operating system on Linux or a Linux guest operating system on Windows. We are not planning to evaluate this type of combination for SAP applications.Additional virtualization solutions
In addition to the virtualization solutions mentioned above, a range of other products for operating system virtualization, hardware virtualization and shared-OS virtualization with isolated containers is offered. Examples are HP Integrity VM, Hitachi Virtage, and Parallels Virtuozzo. These products are not taken into consideration during the SAP validation and release process, and are not tested by SAP. For this reason, we do not support these products. If you use one of these products, ensure that your technology partner provides support in case of problems.
The following applies to these additional virtualization solutions:
If problems such as performance loss or system terminations occur that point to the relevant virtualization solution, or that impair the system availability, it might be required to reproduce the problems on physical hardware. With a system standstill, SAP support will recommend the deinstallation of the virtualization solution as immediate solution.

7 Practical experience with virtualization
The virtualization layer requires additional resources. All virtual machines that run in parallel on a host should require no more than 100% of the memory and 80% of the CPU capacity of the host. The 20% overhead is the minimum for the service overhead that the virtualization requires during the optimal configuration.System calls within a virtual machine result in performance losses. This affects memory management, network communication and disk I/O. A system configuration that has a high paging rate in the operating system or a low cache quality and therefore leads to a high displacement in the database buffer will lead to considerably poorer performance in a virtualized environment.Applications, which scan excessively large memory areas and do not fit in the translation lookaside buffer (TLB) of the chipset due to their size, led to excessive performance losses in the virtualized environment (25% of performance was achieved compared to physical hardware). This problem occurs because the mapping of virtual memory addresses is transferred to physical memory addresses of the Memory Management Unit (MMU). Therefore, MMU is the limiting factor on physical hardware. In a virtualized environment, the MMU is simulated by the hypervisor, and the hypervisor results in a bottleneck due to the excessive mapping.
The performance losses can be corrected only by changing the application logic. You can decrease the performance losses by using more recent processors such as Intel Nehalem or AMD Shanghai and Barcelona.The SAP NetWeaver application server is very suitable for virtualization since the architecture was optimized for a high scalability. The database access is minimized with caches and the communication is outsourced to dispatcher and gateway. Therefore, a virtualized SD dialog application can be as fast as a non-virtualized application. In comparison, applications that actually access the database, or communicate or print using the network, are significantly slower.For release upgrades and Unicode migrations in a virtualized environment, we noticed runtimes that are up to five times longer than the runtimes in a non-virtualized environment.

VMware ESX server
Published benchmarks from Dell, HP, IBM, and Fujitsu Siemens display good performance. During measurements of an individual virtual machine, the physical processors had a performance capacity of approximately 90%.SAP did internal tests with optimal configuration (flat memory model, no protection, and so on). During these tests, we reached about 80% of the maximum capacity of the same server in a non-virtualized environment when all virtual machines are used with full utilization. This applies under the prerequisite that sufficient memory is available, and paging does not occur.

Microsoft Hyper-V
SAP tested its applications on Hyper-V on Windows Server 2008 with four virtual CPUs and on Windows Server 2003 with two virtual CPUs. All internal tests showed a high reliability and stability.During measurements of a single virtual machine, 100% of the performance of the physical machine was reached. No overhead caused by virtualization could be detected.For parallel SAP systems on several virtual machines, we could not detect a loss of performance as long as less than 50% of the possible server utilization was reached. If the server is utilized more than 50%, a significant performance loss was measured within the virtual machine. However, this only occurs when several virtual machines are utilized in parallel.For Hyper-V, we measured 60% of the performance of a non-virtualized machine with full utilization of a server with several virtual machines that run SAP ERP applications.