When Windows Server 2008 shipped with only a beta version of the new “Hyper-V” virtualisation role in the box Microsoft undertook to release a final version within 180 days. I’ve commented before that, based on my impressions of the product, I didn’t think it would take that long and, as Microsoft ran at least two virtualisation briefings this week in the UK, I figured that something was just about to happen (on the other hand I guess they could just have been squeezing the events into the 2007/8 marketing budget before year-end on 30 June).

The big news is that Microsoft has released Hyper-V to manufacturing today.

[Update: New customers and partners can download Hyper-V. Customers who have deployed Windows Server 2008 can receive Hyper-V from Windows Update starting from 8 July 2008.]

Why choose Hyper-V?

I’ve made no secret of the fact that I think Hyper-V is one of the most significant developments in Windows Server 2008 (even though the hypervisor itself is a very small piece of code), and, whilst many customers and colleagues have indicated that VMware has a competitive advantage through product maturity, Microsoft really are breaking down the barriers that, until now, have set VMware ESX apart from anything coming out of Redmond.

When I asked Byron Surace, a Senior Product Manager for Microsoft’s Windows Server Virtualization group, why he believes that customers will adopt Hyper-V in the face of more established products, like ESX, he put it down to two main factors:

• Customers now see server virtualisation as a commodity feature (so they expect it to be part of the operating system).
• The issue of management (which I believe is the real issue for organisations adopting a virtualisation strategy) – and this is where Microsoft System Center has a real competitive advantage with the ability to manage both the physical and virtual servers (and the running workload) within the same toolset, rather than treating the virtual machine as a “container”.

When asked to comment on Hyper-V being a version 1 product (which means it will be seen by many as immature), Surace made the distinction between a “typical” v1 product and something “special”. After all, why ship a product a month before your self-imposed deadline is up? Because customer evidence (based on over 1.3 million beta testers, 120 TAP participants and 140 RDP customers) and analyst feedback to date is positive (expect to see many head to head comparisons between ESX and Hyper-V over the coming months). Quoting Surace:

“Virtualisation is here to stay, not a fad. [… it is a] major initiative [and a] pillar in Windows Server 2008.”

I do not doubt Microsoft’s commitment to virtualisation. Research from as recently as October 2007 indicates only 7% of servers are currently virtualised but expect that to grow to 17% over the next 2 years. Whilst there are other products to consider (e.g. Citrix XenServer), VMware products currently account for 70% of the x86 virtualisation market (4.9% overall) and are looking to protect their dominant position. One strategy appears to be pushing out plenty of FUD – for example highlighting an article that compares Hyper-V to VMware Server (which is ridiculous as VMware Server is a hosted platform – more analogous to the legacy Microsoft Virtual Server product, albeit more fully-featured with SMP and 64-bit support) and commenting that live migration has been dropped (even though quick migration is still present). The simple fact is that VMware ESX and Microsoft Hyper-V are like chalk and cheese:

• ESX has a monolithic hypervisor whilst Hyper-V takes the same approach as the rest of the industry (including Citrix/Xen and Sun) with its microkernelised architecture which Microsoft consider to be more secure (Hyper-V includes no third party code whilst VMware integrates device drivers into its hypervisor).
• VMware use a proprietary virtual disk format whilst Microsoft’s virtual hard disk (.VHD) specification has long since been offered up as an open standard (and is used by competing products like Citrix XenServer).
• Hyper-V is included within the price of most Windows Server 2008 SKUs, whilst ESX is an expensive layer of middleware.
• ESX doesn’t yet support 64-bit Windows Server 2008 (although that is expected in the next update).

None of this means that ESX, together with the rest of VMware’s Virtual Infrastructure (VI), are not good products but for many organisations Hyper-V offers everything that they need without the hefty ESX/VI price tag. Is the extra 10% really that important? And when you consider management, is VMware Virtual Infrastructure as fully-featured as the Microsoft Hyper-V and System Center combination? Then consider that server virtualisation is just one part of Microsoft’s overall virtualisation strategy, which includes server, desktop, application, presentation and profile virtualisation, within an overarching management framework.

Guest operating system support

At RTM the supported guest operating systems have been expanded to include:

• Windows Server 2008 32- or 64-bit (1, 2 or 4-way SMP).
• Windows Server 2003 32- or 64-bit (1, or 2 way SMP).
• Windows Vista with SP1 32- or 64-bit (1, or 2 way SMP).
• Windows XP with SP3 64-bit (1, or 2 way SMP), with SP2 64-bit (1, or 2 way SMP) or with SP2 32-bit (1 vCPU only).
• Windows Server 2000 with SP4 (1 vCPU only).
• SUSE Linux Enterprise Server 10 with SP1 or 2, 32- or 64-bit.

Whilst this is a list of supported systems (i.e. those with integration components to make full use of Hyper-V’s synthetic device driver model), others may work (in emulation mode) but my experience of installing the Linux integration components is that it is not always straightforward. Meanwhile, for many, the main omissions from that list will be Red Hat and Debian-based Linux distributions (e.g. Ubuntu). Microsoft isn’t yet making an official statement on support for other flavours of Linux (and the Microsoft-Novell partnership makes SUSE an obvious choice) but they are pushing the concept of a virtualisation ecosystem where customers don’t need to run one virtualisation technology for Linux/Unix operating systems and another for Windows and its logical to assume that this ecosystem should also include the leading Linux distribution (I’ve seen at least one Microsoft slide listing RHEL as a supported guest operating system for Hyper-V), although Red Hat’s recent announcement that they will switch their allegiance from Xen to KVM could raise some questions (it seems that Red Hat has never been fully on-board with the Xen hypervisor).

Performance and scalability

Microsoft are claiming that Hyper-V disk throughput is 150% that of VMware ESX Server – largely down to the synthetic device driver model (with virtualisation service clients in child partitions communicating with virtualisation service providers in the parent partition over a high-speed VMBus to access disk and network resources using native Windows drivers). The virtualisation overhead appears minimal – in Microsoft and QLogic’s testing of three workloads with two identical servers (one running Hyper-V and the other running direct on hardware) the virtualised system maintained between 88 and 97% of the number of IOPS that the native system could sustain and when switching to iSCSI there was less than a single percentage point difference (although the overall throughput was much lower). Intel’s vConsolidate testing suggests that moving from 2-core to 4-core CPUs can yield a 47% performance improvement with both disk and network IO scaling in a linear fashion.

Hardware requirements are modest too (Hyper-V requires a 64-bit processor with standard enhancements such as NX/XD and the Intel VT/AMD-V hardware virtualisation assistance) and a wide range of commodity servers are listed for Hyper-V in the Windows Server Catalog. According to Microsoft, when comparing Hyper-V with Microsoft Virtual Server (both running Windows Server 2003, with 16 single vCPU VMs on an 8-core server), disk-intensive operations saw a 178% improvement, CPU-intensive operations returned a 21% improvement and network-intensive operations saw a 107% improvement (in addition to the network improvements that the Hyper-V virtual switch presents over Virtual Server’s network hub arrangements).

Ready for action

As for whether Hyper-V is ready for production workloads, Microsoft’s experience would indicate that it is – they have moved key workloads such as Active Directory, File Services, Web Services (IIS), some line of business applications and even Exchange Server onto Hyper-V. By the end of the month (just a few days away) they aim to have 25% of their infrastructure virtualised on Hyper-V – key websites such as MSDN and TechNet have been on the new platform for several weeks now (combined, these two sites account for over 4 million hits each day).

It’s not just Microsoft that thinks Hyper-V is ready for action – around 120 customers have committed to Microsoft’s Rapid Deployment Programme (RDP) and, here in the UK, Paul Smith (the retail fashion and luxury goods designer and manufacturer) will shortly be running Active Directory, File Services, Print Services, Exchange Server, Terminal Services, Certificate Services, Web Services and Management servers on a 6-node Hyper-V cluster stretched between two data centres. A single 6-node cluster may not sound like much to many enterprises, but when 30 of your 53 servers are running on that infrastructure it’s pretty much business-critical.

Looking to the future

So, what does that future hold for Hyper-V? Well, Microsoft already announced a standalone version of Hyper-V (without the rest of Windows) and are not yet ready to be drawn on when that might ship.

In the meantime, System Center Virtual Machine Manager 2008 will ship later this year, including suppoort for managing Virtual Server, Hyper-V and VMware ESX hosts.

In addition, whilst Microsoft are keeping tight-lipped about what to expect in future Windows versions, Hyper-V is a key role for Windows Server and so the next release (expected in 2010) will almost certainly include additional functionality in support of virtualisation. I’d expect to see new features include those that were demonstrated and then removed from Hyper-V earlier in its lifecycle (live migration and the ability to hot-add virtual hardware) and a file system designed for clustered disks would be a major step forward too.

In conclusion…

Hyper-V may be a version 1 product but I really do think it is an outstanding achievement and a major step forward for Microsoft. As I’ve written before, expect Microsoft to make a serious dent in VMware’s x86 [and x64] virtualisation market dominance over the next couple of years.