Virtualization has taken off like wild fire, and now organizations are in the process of virtualizing tier-1 applications like Exchange 2010. However, sizing and designing Exchange 2010 for a virtualized environment requires some additional care and thought versus a traditional physical server deployment. Critical sizing requirements like memory, vCPUs, and storage performance/type have unique guidelines when deployed on vSphere 4.x.
VMware has published a VERY lengthy guide for Exchange architects that covers all of the unique aspects for sizing and designing your Exchange 2010 environment for vSphere 4.x. I highly encourage anyone doing such a deployment to thoroughly read the guide, found here. The whitepaper includes complex enterprise configurations supporting 16,000 users with 4-node DAG clustering.
Some example key recommendations include:
- Only allocate multiple vCPUs to a virtual machine if the anticipated Exchange workload can truly take advantage of all the vCPUs.
- If the exact workload is not known, size the virtual machine with a smaller number of vCPUs initially and increase the number later if necessary.
- For performance-critical Exchange virtual machines (i.e., production systems), try to ensure the total number of vCPUs assigned to all the virtual machines is equal to or less than the total number of cores on the ESX host machine.
- Don’t over commit memory
- Spread the heavy I/O systems across several LUNs
- Use eagerthickzero (EZT) VMDK files
- Use VMXnet3 driver
- Use PVSCSI adapter
Additional Exchange 2010 and vSphere resources:
Scale-Out Performance of Exchange 2010 Mailbox Servers
Scale-Up Performance of Exchange 2010
Exchange 2010 Disk I/O on vSphere
Dell Exchange 2010 on vSphere 4
Exchange 2010 on vSphere
DAG performance on vSphere 4.1
Mailbox VM I/O Sizes