A white paper has been published that examines how Microsoft Exchange Server 2010 performs on vSphere 5 in terms of scaling up (adding more virtual CPUs) and scaling out (adding more VMs).  Having the choice to scale up or out while maintaining a positive user experience gives IT more flexibility to right-size system deployments and maximize total cost of ownership with respect to licensing and hardware purchases.

Testing shows the effectiveness of vSphere 5 to add compute power by scaling up Exchange Server VMs, in increments, from 2 to 12 virtual CPUs. This allowed the total number of very heavy Exchange users to increase from 2,000 to 12,000 while sendmail latency remained well within the range of acceptable user responsiveness. Processor utilization remained low, at about 15% of the total host processing capacity for 12,000 very heavy Exchange users.

Testing also shows that scaling out to eight Exchange Server VMs supports a workload of up to 16,000 very heavy users, with the load consuming only 32% of the ESXi host processing capacity.

Additional tests were undertaken to show the performance improvements of vMotion and Storage vMotion in vSphere 5. vMotion migration time for a 4-vCPU Exchange mailbox server VM showed a 34% reduction in vSphere 5 over vSphere 4.1. Storage vMotion migration time for a 350GB database VMDK showed an 11% reduction in vSphere 5 over vSphere 4.1.

For the full paper, see Microsoft Exchange Server 2010 Performance on vSphere 5.