SAP Note

Header Data

Symptom

You want to run SAP virtualized on Red Hat Enterprise Linux (RHEL) on KVM virtual machines

Other Terms

Linux, Red Hat, RHEL, KVM, RHEV

Reason and Prerequisites

You want to configure your Red Hat Enterprise Virtualization or Red Hat Enterprise Linux KVM virtualization environment to fit perfectly to SAP

Solution

Red Hat offers two separate products that include KVM virtualization technology:

l Red Hat Enterprise Virtualization (RHEV)

l Red Hat Enterprise Linux (RHEL)

Support for running SAP on Red Hat Enterprise Virtualization (RHEV)

With RHEV 3 (http://www.redhat.com/virtualization/rhev/server/) running SAP production environments on virtual machines running RHEL 5 or RHEL 6 is supported. The following RHEV releases are currently supported:

l RHEV 3.X

Please note: RHEV 2.x is not supported since it lacks the monitoring functionality required by SAP. A "Red Hat Enterprise Linux for SAP Business Applications" subscription is required for each RHEL guest running SAP software.

Support for running SAP on RHEL with KVM

KVM has been included into RHEL since release 5.4. SAP supports KVM in the following RHEL releases:

l RHEL 5.4 and newer (5.5, 5.6, 5.7, 5.8, 5.9, 5.10) l RHEL 6.1 and newer (6.2, 6.3, 6.4, 6.5) l RHEL 7.0 and newer

Please follow the Red Hat Enterprise Linux virtualization guides available at https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/ for instructions on how to configure the virtualization environment. When using RHEL as the hypervisor you need to have an active Red Hat subscription for "Red Hat Enterprise Linux for SAP Business Applications" to be able to install the vhostmd monitoring package. All RHEL guests systems running SAP software need "Red Hat Enterprise Linux for SAP Business Applications" subscriptions as well. KVM is only supported on the x86_64 platform.

Virtualization Method

KVM only works on servers with Processors that offer hardware support for virtualization (Intel VT-X or AMD-V). It is not possible to run para-virtualized guests with KVM on systems without processors that don't provied hardware virtualization support. Since most hardware vendors disable the hardware virtualization features of their servers per default for security reasons, please make sure that those hardware virtualization features are enabled in the BIOS before you begin to set up the KVM host system.

Supported Guest Operating Systems

    1400911 - Linux: SAP on Red Hat KVM - Kernel-based Virtual Machine  

Version   17     Validity: 12.02.2015 - active   Language   English (Master)

Released On 16.02.2015 09:46:19

Release Status Released for Customer

Component BC-OP-LNX-RH Red Hat Linux

BC-OP-LNX Linux

Priority Recommendations / Additional Info

Category FAQ

Other Components

Only RHEL 5.x and RHEL 6.x for x86_64 are supported as guest Operating System for running SAP servers on RHEL6/KVM or RHEV3.

Setting up the SAP Host monitoring on RHEV 3

SAP requires that some metrics of the host system running the virtual machines can be monitored from the guest system. Please follow the instructions In the "Enabling SAP monitoring for a virtual machine from the Administration Portal" in the Administration Guide for your RHEV release to set up the SAP host monitoring for virtual machines running SAP applications. In addition you need to install the "vm-dump-metrics" (available via the "RHEL for SAP" channel) package in each guest running SAP software.

Setting up the SAP Host Monitoring on RHEL 5/6/7

In order to provide this functionality you need to install the "vhostmd" package in the host and the "vm-dump-metrics" package in all your guest systems running SAP. To be able to install those packages the host and guest need to be subscribed to the "RHEL for SAP" channel. "vhostmd" uses libvirt to gather the host metrics. Therefore it is necessary that all guests running SAP applications are managed via the standard libvirt tools (virsh, virt-manager, ...). Using "quemu-kvm" directly to manage guests is not supported.

On the host please install the vhostmd daemon with the following command:      $ yum install vhostmd

On RHEL 7 please make sure that you have at least vhostmd-0.5.11.el7_0 installed on the host. On the guest install the vm-dump-metrics tool with the following command:      $ yum install vm-dump-metrics The vhostmd daemon provides the required metrics from the host to the guest via a virtual disk device. You need to add this virtual disk device as an additional storage device to the configuration of all your guest VMs. This can either be done through the "virt-manager" graphical management tool, or by adding the following entry to the XML-configuration files of your VMs:     <disk type='file' device='cdrom'>       <driver name='qemu' type='raw'/>       <source file='/dev/shm/vhostmd0'/>       <target dev='hdX' bus='ide'/>       <readonly/>     </disk> (Please choose an available device name instead of "hdX" for the storage device) You need to restart the VM after the new storage device has been added. Please install and run the "vm-dump-metrics" (available via the "RHEL for SAP" channel) tool in the guest to verify that the metrics can be read successfully.

Storage configuration

For RHEL5/6 KVM host it is recommended to place the storage for KVM virtual machines on raw partitions or LVM devices. Do not use a file as virtual device for a virtual machine. If you run an SAP database instance on such a file based virtual machine the I/O performance will drop dramatically compared to a raw setup. We also advise you to use an external storage for the virtual machines when using a SAP database instance performance wise. For SAP application servers, local disks are sufficient.

Performance Tuning Guidelines

To achieve the best performance on the virtual machines please use the following guidelines:

l change the I/O scheduler to "deadline" on the host; on the guests, please use the "noop" scheduler; to change the I/O scheduler add "elevator=deadline" to the kernel boot options on the host and "elevator=noop" to the kernel boot options on the guests

l use the "virtio" driver to when configuring the storage and network devices for the guests

l on RHEL5 make sure that the disk caching mechanism of the hypervisor is turned off. To do this you need to edit the XML-configuration file of the KVM guest and add the following line to all disk-device entries except the one you added for the monitoring above:

           <driver name='qemu' cache='none'/>            The entries for the disk-devices should then look similar to the following:                < disk type='block' device='disk'>             <driver name='qemu' cache='none'/>                  < source dev='/dev/sde1'/>                  < target dev='vda' bus='virtio'/>                </disk>            On RHEL6 the caching is turned off by default, so this change is no longer necessary.

l on RHEL6 do not change the processor model for the virtual machines from the default setting

Certified Hardware

You may only run your host system on hardware which is certified for Linux KVM environments. Please have a look at the release notes of the LinuxLab Hardware Partners and check which servers are certified for KVM explicitly. A list of notes of the the released and certified hardware of the LinuxLab Hardware Partners is available in the "Related Notes" section of SAP Note 171356.

Validity

This document is not restricted to a software component or software component version

References

This document refers to:

SAP Notes

This document is referenced by:

SAP Notes (10)

1706801   SYB: Sybase ASE released for virtual systems

1631106   Red Hat Enterprise Linux for SAP Business Applications

1496410   Red Hat Enterprise Linux 6.x: Installation and Upgrade

1426182   Support of Oracle Database for XEN and KVM

1379130   Linux: Released NEC hardware

1130801   DB6: Virtualization of IBM DB2 for Linux, UNIX, and Windows

1122387   Linux: SAP Support in virtualized environments

1102124   SAPOSCOL on Linux: Enhanced function

1048303   Red Hat Enterprise Linux 5.x: Installation and upgrade

171356   SAP Software on Linux: General information

1122387   Linux: SAP Support in virtualized environments

1102124   SAPOSCOL on Linux: Enhanced function

1379130   Linux: Released NEC hardware

1496410   Red Hat Enterprise Linux 6.x: Installation and Upgrade

1426182   Support of Oracle Database for XEN and KVM

1631106   Red Hat Enterprise Linux for SAP Business Applications

1706801   SYB: Sybase ASE released for virtual systems

1048303   Red Hat Enterprise Linux 5.x: Installation and upgrade

1130801   DB6: Virtualization of IBM DB2 for Linux, UNIX, and Windows

171356   SAP Software on Linux: General information