posted

0 Comments

This is a follow up to an earlier blog where  we tested a SAP HANA system on stretched cluster in VMware Cloud on AWS.  Testing showed that running the application and database server virtual machines of the same SAP system within the same Availability Zone in a stretched cluster scenario can improve performance (the degree depends on the workload and the business impact depends on the service level agreements). In this blog we show an example configuration of a compute policy in VMware Cloud on AWS to achieve this co-location,

VMware Cloud on AWS is not supported for SAP workloads at this time.  Please stay tuned to https://twitter.com/vmwarecloudaws .

Compute Policies

Compute policies in VMware Cloud on AWS provide a way to specify how the vSphere Distributed Resource Scheduler (DRS) should place virtual machines on hosts in the SDDC. You can create a VM-Host affinity policy which describes a relationship between a category of virtual machines and a category of hosts. This can be used to keep the application and database server virtual machines of the same SAP system on the hosts in the same Availability Zone.

As mentioned in VMware documentation: affinity policies in VMware Cloud on AWS SDDC are not the same as the vSphere DRS affinity rules you can create on premises. They are preferential policies.

“Compute Policies” is a an entry that appears in the vSphere client in VMware Cloud on AWS under Menu -> Policies and Profiles 

 

 

An overview of the process to create a VM-Host affinity policy to keep an SAP system (database and application server VMs) in the same Availability Zone is summarized below.

 

The Appendix below shows the steps in more detail with the vSphere client menu paths.

Summary

  • In a previous blog, testing showed that for some workloads performance of a multi-tier SAP HANA system can benefit from co-locating the application and database server VMs in the same AWS Availability Zone in a stretched cluster configuration.
  • VMware Cloud on AWS has compute policies which can be used to keep the application and database server virtual machines of the same SAP system on hosts in the same Availability Zone. This is different from vSphere DRS affinity rules you can create on premises.
  • The compute policy requires creating a VM-Host affinity to which host and VM tags are assigned.

 

Appendix VM– Host Affinity Example Configuration Steps