The Exchange group's obsession with direct-attached storage (DAS) is going to cost Microsoft market share in the virtualization space.
Quick quiz: How many Exchange servers does it take to provision 300 highly available Exchange mailboxes? The answer is six - and that's if you put client access and hub transport roles on the same servers. There are some good reasons for that sort of suprising number (although it would be nice to be able to put more than one role on a clustered mailbox server). But when I look at that ratio of servers to users, I see that Exchange is a classic candidate for server virtualization. Indeed Microsoft now formally supports Exchange on Hyper-V, as well as third-party virtualization platforms.
Obviously VMWare isn't alone in their vision of a virtualized data center - Microsoft also realizes that in the very near future, the default platform for new applications will be virtualized even in the most conservative of IT environments. Hence the heavy investment and incentives to adopt Hyper-V - they want customers to use Microsoft's hypervisor - not anyone else's. That's great news for IT buyers. Competition nearly always results in better value for the consumer.
Which makes the the Exchange team's latest spreadsheet effort a little more baffling than usual. This spreadsheet is supposed to calculate the TCO of direct-attached storage to SAN storage. There's a few warts on their approach even leaving out the virtualization discussion:
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First, VSS clones and snapshots complement, rather than compete with CCR (since it allows rapid recovery from a variety of external threats, and error conditions that CCR cannot). After all, SQL Server has had CCR-like functionality for many years now. Lots of people use it (primarily on their SANs), but the SQL Server team does not claim it's a direct replacement for a rapid backup and restore system that leverages VSS or VDI. And neither CCR or database mirroring preclude the use of a SAN.
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Second, there's no way a generic spreadsheet can estimate the TCO of a given VSS-protected Exchange install, since each SAN vendor implements their VSS Provider differently.
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Lastly, their effort leaves out a number of factors that are included in more evolved TCO studies (which show time after time that shared storage is more cost-efficient than direct-attached storage silos).
But what's really got me scratching my head is how strategically disconnected the Exchange team is from the rest of Microsoft (and indeed the rest of the IT world) when it comes to virtualization (which currently requires a storage network if you want to do high availability, live or quick migration, or any of the good stuff layered on top of it). Most folks deploying Exchange today will expect their installation to last for a 3 to 5 year lifecycle. During that time, most organizations will either deploy a new virtualization platform in production, or move forward with virtualizing more production applications. So people who decide to deploy Exchange on direct-attached storage will end up buying entirely new storage to take advantage of the incredible ROI that virtualization offers.
Keep in mind that both of the major virtualization vendors offer simple methods to migrate existing production servers to their virtual platforms (and even free or inexpensive tools to determine likely candidates for virtualization). So even while some folks have decided to deploy Exchange on physical servers, a lot of those same folks will decide to move it to virtualized servers in the next year or so. A downturn in the economy is only going to accelerate that process as people seek to deliver more services with less infrastructure.
The funny thing is that people planning a virtualized Exchange environment pretty much ignore the DAS message already. The only folks considering deployment of Exchange on DAS are the very same folks who Microsoft hopes will be net new virtualization customers (deploying on Hyper-V) over the next 12 to 36 months (after they've released Windows 08 R2 and the features that will put Hyper-V on par with VMWare). And the fact that they will be on DAS will prevent virtualization.
Dissonance in a large company like Microsoft is not unusual. But I have to wonder when they'll realize they're shooting themselves in their virtual foot.
