Hyper-V 2.0: Microsoft's Virtualization Offering Grows Up
Among the new features, finally, is Live Migration, which provides the ability to move running virtual machines (VMs) between physical servers without interrupting their operation.
If the feature sounds familiar that's because it probably is: It's the equivalent of VMware's VMotion, which the virtualization giant first introduced in 2003.
That is the way that Microsoft works: Identify a market, enter it with a feature-poor product (often bundled with another product) and then incrementally add features to catch up with the competition. It's a strategy the company has pursued countless times and one that has often been successful as competitors to Internet Explorer and Office, among others, learned to their cost. Since Hyper-V is part of Windows Server 2008 (and Windows Server 2008 R2) it is going to be installed on a great many servers, and it's bound to be widely used. There is no reason why the strategy shouldn't be successful in this market too, if it can keep introducing new features to catch up with VMware.
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In System Center, Microsoft's management system, and its new Virtual Machine Manager module, the company has a ready made platform to compete with VMware's own management platform. "The ability to manage your virtual estate is very important, and System Center will be a very valuable management tool," said Roy Illsley, a senior research analyst at the Butler Group. Using the Virtual Machine Manager System Center module, it is possible to manage Hyper-V- and VMware-based VMs, and to carry out operations such as moving them between physical machines, from a single console or even automatically by policy. Support for machines virtualized using Citrix's Xen hypervisor is also planned. "By contrast, VMware's management capabilities are good for controlling VMware products, but that's the limit," said Illsley.
Live Migration was left out of the original Hyper-V in June because of difficulties with file systems, and Microsoft attempted to cover the omission by offering Quick Migration instead. Quick Migration requires saving the state of a running VM to disk before the storage connectivity can be moved from one physical machine to another and restoring the saved state from storage to memory. The move process can take as little as 6 seconds for a 512Mb virtual machine, but service is still interrupted.
The fact that Live Migration has been included in the second version of Hyper-V shows Microsoft believes it is a key feature. To be able to offer it, the company has had to introduce a new shared file system called Clustered Shared Volumes. But Illsley warned that Live Migration will not appeal to everyone. "It's a useful capability, but remember that it is only interesting in a data center environment where you have shared storage. And it only really works with chips of the same generation. You can't do it between physical machines with Intel and AMD chips, or between Intel 7200 and 7300 chips without losing functionality."
Microsoft appears to understand this and has added a large number of other new features as well. One incremental enhancement is scalability. Specifically, Hyper-V 2.0 will support up to 32 logical processors, compared to only 16 in Server 2008's Hyper-V when it was released, and 24 when it was updated in September. As mentioned earlier, Microsoft is slowly but surely increasing the power of Hyper-V, and it's likely this scalability will be further increased in the future.
Microsoft has also promised the ability to add and remove .vhd files, as well as pass-through disks attached to a virtual SCSI controller on a running VM, without requiring a reboot. This "hot" add and remove capability makes thin provisioning much easier to implement, Illsley said. Thin provisioning is potentially one of the most effective ways of preventing the storage requirements of a virtualized environment from spiraling out of control, by allocating storage to applications without actually provisioning it until it is needed. Hot add/remove also provides more flexibility in data center backup scenarios as well as new scenarios in complex Exchange and SQL Server deployments, Microsoft claims. It will also be possible to boot a computer from a .VHD file stored on a local hard disk.
There are several improvements in the way memory is used under Hyper-V 2.0 as well. The hypervisor itself will use a smaller proportion of total system memory, Microsoft promises, which leaves more for guest operating systems. And dynamic memory allocation will mean that virtual machines that don't need memory at a given time can relinquish it back to a pool and reallocated to a virtual machine that needs more.
The new Hyper-V is also being touted as more efficient. Hyper-V 2.0 will support Second level Address Translation (SLAT), improving VM performance and reducing the CPU load on some hardware. It also uses less power compared to the original Hyper-V.
VMs should benefit from better network performance thanks to the extension of TCP Offload and Jumbo Frames both features of Windows Server 2008 to VMs. TCP offload enables the NIC of the host machine to carry outTCP processing instead of the main processor doing it, while Jumbo Frames allow 6 times larger payloads per packet.
Finally, Microsoft has been working on improvements to presentation virtualization and Virtual Desktop Infrastructure (VDI) essentially allowing remote users to operate a virtualized desktop device or an individual application running at a central location. When Windows 7 users access applications running remotely, the apps will look and feel like they are locally installed complete with the Aero Glass interface and they will be accessible from the Start menu, Microsoft said.
For the moment, Hyper-V is still in its infancy, and traditionally it's not until version 3 of a product that Microsoft seriously challenges incumbents in a particular market. But with the introduction of Live Migration in Hyper-V 2.0, and its combination with System Center, Microsoft is already building a serious virtualization platform that may well become a dominant force in the market.