A colleague and I were recently discussing the upcoming release of Hyper-V 3.0, which will debut in Windows Server 8. He asked if I thought that Hyper-V 3.0's new features would be enough to sway administrators who are currently virtualizing Exchange via VMware vSphere. I don't have a crystal ball, but I do have a few thoughts on how admins will respond to Hyper-V 3.0.
First off, many admins will undoubtedly continue virtualizing Exchange on VMware vSphere. There are a number of reasons why:
- Hyper-V has a reputation as an immature product that is not suitable for enterprise environments. That stigma is sure to follow Hyper-V for some time, even after the release of Version 3.0.
- Organizations running VMware have likely invested considerable capital into their existing virtualization infrastructures and may be reluctant to abandon them.
- Some IT shops will stick with VMware purely because of vendor loyalty.
- Some organizations will be hesitant to switch to Hyper-V because of the difficulties involved in moving a mission-critical application such as Exchange Server to a different virtualization platform.
As you can see, there are several reasons why Exchange administrators will stick with VMware. It's difficult to ignore several new Hyper-V features, however, especially when you consider how they can benefit Exchange shops.
Exchange and Hyper-V 3.0: Scalability improvements
Many of the virtualization improvements included in Hyper-V 3.0 focus on scalability. Previously, virtual machines (VMs) that ran on Hyper-V were limited to four virtual CPUs and 32 GB of RAM. These limitations alone caused many companies to think twice about hosting Exchange on Hyper-V.
In Hyper-V 3.0, VMs can now be provisioned with up to 32 virtual CPUs and up to 512 GB of RAM. In addition, Hyper-V 3.0 will support virtual hard drives up to 16 TB. These scalability improvements should easily accommodate even the largest Exchange 2010 mailbox servers.
Exchange and Hyper-V 3.0: Improvements to Live Migration
Another aspect of Hyper-V 3.0 that's sure to impress Exchange admins is that Microsoft has redesigned both Live Migration and Live Storage Migration. Live Migration was first introduced in Windows Server 2008 R2 as an alternative to VMware's Vmotion. The feature allows admins to move a VM from one clustered host server to another with no downtime.
The problem was that first iteration of Live Migration could only move one VM at a time. If a host server contained a large number of VMs, the process of moving them to another host could be painfully slow. In contrast, in Hyper-V 3.0, you'll be able to concurrently move multiple VMs between host servers with no downtime.
Exchange and Hyper-V 3.0: Affinity rules and failover improvements
Exchange admins should also benefit from affinity and anti-affinity rules in Hyper-V 3.0. In Exchange Server, there are often VMs that should never reside on a common virtualization host server. For example, if you're distributing workloads across multiple client access servers (CAS), it doesn't make sense from both performance and fault-tolerance standpoints to host multiple servers on a single virtualization host.
The problem here is that in failover situations, VMs that were purposefully isolated from one another may end up running on a common host. You can configure Hyper-V 3.0's affinity and anti-affinity rules so that a group of VMs can fail over collectively (where all your Exchange VMs can fail over as a group) or so that certain machines always reside on separate hosts.
Microsoft has made other improvements to failover. For starters, Hyper-V clusters will be able to support up to 63 host servers and collectively host up to 4,000 VMs. More importantly, Hyper-V 3.0 lets you prioritize VMs in a failover situation.
Suppose for example that a host server failed and all the VMs running on the host were moved to another host server within the cluster. If the remaining host server is already hosting some VMs, it may not have the system resources to host all of the VMs that were previously running on the failed server.
Prioritization lets you specify which VMs you deem most important. If there is a shortage of system resources, then high-priority VMs like mailbox servers can take priority over less important virtual machines like redundant hub transport servers.
It seems that Hyper-V has finally become a truly enterprise-class hypervisor. Not every organization will switch to Hyper-V, but with these significant improvements, many Exchange shops are sure to at least consider switching from VMware.
ABOUT THE AUTHOR:
Brien Posey is an eight-time Microsoft MVP with two decades of IT experience. Before becoming a freelance technical writer, Brien worked as a CIO for a national chain of hospitals and healthcare facilities. He has also served as a network administrator for some of the nation’s largest insurance companies and for the Department of Defense at Fort Knox.
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