Exchange Server 2010 On a vSphere 5 Host Supporting 16K Heavy Users? No Problem!

I’ve been a fan of the VROOM! blog for some time as often time I keep hearing “you can’t do that with a virtual machine” and I turn around and say “someone already did — look!”.  So now that both Exchange 2010 and vSphere 5 have been released, what’s possible?  The VROOM! team’s whitepaper is here, but I walked to take a quick walk through some key areas and provide a summary.

The physical host used was a Dell 910 (4 CPUs) with 256GB of RAM running vSphere 5.   The first test was to see how much acceptable load could be sustained using a single VM.  By “acceptable” it is meant that latency for each end user is kept below 500ms for 95% of all transactions.

As illustrated above,  vSphere 5 was able to provide a 13% improvement in latency over vSphere 4.1 at a capacity of 8,000 users.  vSphere 4.1 can only support 8 vCPUs in a guest, but vSphere 5 didn’t have this limitation.  vSphere 5 supported 12,000 users on the single 12-vCPU VM, while using less than 15% of the CPU capacity on the host.

Now it has been demonstrated with other applications, that you can often achieve more transactions on a physical host, but using several smaller VMs as opposed to a single VM, and the same is true here.  By using 8 different virtualized Exchange servers (4 mailbox, 4 client/hub) on the same physical host, the team was able to support 16,000 heavy Exchange users with 95% of transactions having a latency of less than 200 ms (anything under 500ms is generally considered acceptable).  During this 16,000 user test, only 32% of the CPU capacity of the physical host server was consumed:

But if you had to vMotion an Exchange server you’d create problems for the end users, right?  Not in these drills and probably not in most environments either.  The vMotion of an Exchange server took 47 seconds (71 seconds with vSphere 4.1) and the number of end user task exceptions was ZERO.

Compared to vSphere 4.1, vSphere 5 shows a 34% improved in vMotion migration time and an 11% improvement in Storage vMotion time.

In all, it’s pretty clear that vSphere 5 is a strong platform for Exchange 2010 and many other applications as well.  Virtualization can provide consolidation (density) and scalability benefits, as well as provide many new options for high availability, disaster recovery, and much more.   Virtualization itself is not cloud computing, but the more we virtualize, the more workloads we have for which we can consider for taking advantage of the benefits that are possible with cloud computing.

One Response to Exchange Server 2010 On a vSphere 5 Host Supporting 16K Heavy Users? No Problem!

  1. Connecticut says:

    In more complex CPUs than the one described here, multiple instructions can be fetched, decoded, and executed simultaneously. This section describes what is generally referred to as the “classic RISC pipeline”, which in fact is quite common among the simple CPUs used in many electronic devices (often called microcontroller). It largely ignores the important role of CPU cache, and therefore the access stage of the pipeline.

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