Last week I wrote about booting Windows from a USB flash drive.

This had been a “pet project” of mine for a few months and, just after I finally got around to doing it, Stephen Rose blogged about a tool to help you prepare the USB drive to boot from VHD. Oh well, that’s life – I can’t get the time back – but anyway, I enjoyed working out the answers for myself.

Today, I’ve seen a post from the Windows virtualisation team about the release of Hyper-V Server 2008 R2. It’s mostly a rehash of the long-running argument that Hyper-V (Server) costs less than ESX (i) and it probably does, even when factoring in the cost of the management tools but the real cost savings with virtualisation come from reduced power consumption (which will depend on the hardware used, and the consolidation ratios achieved) and operational improvements (i.e. not just running a virtualised infrastructure in the same way as for a physical one) so I’d take the messages from either Microsoft or VMware with a pinch of salt. Perhaps understandably for software companies, both focus too much on the cost of hardware and software rather than the cost of service delivery, which is what really matters to IT Managers.

More significantly from my point of view, the Microsoft’s Windows Virtualization Team also announced formal support for booting Hyper-V Server 2008 R2 from flash memory:

“Microsoft Hyper-V Server 2008 R2 includes the unique ability (compared to Windows Server Hyper-V) to boot from flash. We’re making the documentation available to our OEM partners as part of the OEM Preinstallation Kit (OPK). Boot from flash is specifically designed for our OEM partners who want to ship an embedded Hyper-V hypervisor and thus will be supported via our OEM partners.”

“So what”, you may ask. Well, this means that Hyper-V Server servers can now be diskless (e.g. boot from SAN) and treated as a commodity appliance. For organisations that still see a version of Windows as an operating system (any version of Windows – even if it’s just server core running Hyper-V) and so internal cross-charging mechanisms effectively tax virtualisation hosts as a full operating system, this is a step forward. It gets even better when considering that Hyper-V Server 2008 R2 is based on the Enterprise Edition of Windows Server (the previous version was based on Standard Edition) so it supports clustering and hence live migration.

I had heard something about flash support from a contact at HP (after I got it working!) but had seen nothing formally via the MVP programme; however this is the way that OEMs “embed” VMware ESXi (at least one vendor told me that they use an internally-mounted USB drive for ESXi – I’m not sure if that’s the way it works for all of them). Of course, running the OS from an inexpensive USB flash drive may be fine for a hypervisor that, once loaded into memory, requires little disk access but it’s certainly not a recommended solution for a full operating system – for that you would need better quality flash memory, such as a solid state disk (SSD).