A look at the virtualization software from VMware and Microsoft. Is vSphere or Hyper-V a better fit for your company?
In the world of x86 server virtualization, theres no doubt that VMware's vSphere
dominates. This 2010 IDC virtualization report
shows VMware as the only company in the upper right segment of Gartners Magic Quadrant.
However Citrix (with Xen Server) and Microsoft (with Hyper-V) are close behind. So, could the Microsoft solution be good enough for organizations that dont want to follow the VMware path?
Hyper-V was originally launched by Microsoft in July 2008 as an update to Windows Server 2008 and is now available as a stand-alone product (Microsoft Hyper-V Server 2008 R2) or within versions of Windows Server 2008 and Windows Server 2008 R2. Hyper-V can also be installed on the pared down Windows Server 2008 Core versions. These systems provide a much smaller server footprint but no local GUI management.
Prior to the release of Hyper-V, Microsoft had gained experience in server virtualization after purchasing the Virtual PC software from Connectix. This was released and is still available as Microsoft Virtual Server 2005 R2; the history of both Hyper-V and Virtual Server is evident in their use of the same VHD disk format.
Although Microsoft doesnt have the same length of experience as VMware (their first product, VMware Workstation was released in 1999), could Hyper-V be a better choice than vSphere for some companies?
vSphere vs. Hyper-V: Cost
Today, standalone Hyper-V Server 2008 (R2) is available for free download from Microsofts website. For customers who have already purchased a version of Windows Server 2008 (R2), Hyper-V is automatically available as a feature within the product.
We shouldnt forget that both VMware and Citrix offer free versions of their products too. However in both cases, certain features are not available with the free releases.
For example, more advanced deployments may want to make use of features for high availability. With vSphere, vMotion (which enables the migration of guests between physical servers) is not available in the free releases; Hyper-V currently offers Live Migration (an equivalent feature) for free.
vSphere is licensed at four levels in addition to the free version. These are Standard, Advanced, Enterprise and Enterprise Plus. Pricing is based on physical processor and shown below. These prices are list and taken from VMwares website on February 2011.
vSphere Standard with 1 year production support - $1318.00
vSphere Advanced with 1 year production support - $2806.00
vSphere Enterprise with 1 year production support - $3594.00
vSphere Enterprise Plus with 1 year production support - $4369.00
These costs dont include any licenses for guest operating systems. This compares to list prices for releases of Windows 2008 Server:
Windows Server 2008 R2 Standard - $1029.00
Windows Server 2008 R2 Datacenter - $2999.00
The 2008 DataCenter license includes the rights to run an unlimited number of virtual instances of the Windows 2008 operating system at either Standard, Enterprise or Datacenter versions.
While direct comparisons arent truly possible, it can be seen that Microsoft is aiming to make the cost of using Hyper-V extremely attractive to customers who already use their Datacenter products, and that Hyper-V Server 2008 R2 provides a high level of functionality for no charge.
Clearly cost isnt the only factor in choosing a software product. Available features score heavily in determining whether a virtualization solution meets requirements.
Its true that Hyper-V is feature-lite in comparison to vSphere.
Hyper-V with the R2 release represents only the second iteration of the hypervisor, whereas VMware has reached version 4.1 of vSphere, with a new release expected later this year. However Microsoft is committed to adding new features and the SP1 release of Hyper-V Server 2008 R2 and Windows Server 2008 R2 have now been released to manufacturing (RTM).
This version will add Dynamic Memory and RemoteFX features (advanced memory management and graphics improvement features respectively), bringing performance improvements and making Hyper-V more suitable for VDI (Virtual Desktop Infrastructure).
Of course Hyper-V offers all the standard virtualization features. Hyper-V Server 2008 R2 supports up to 384 virtual guests, enables snapshots to be taken and, with the R2 release, provides both Live Migration and Host Clustering.
Live Migration is similar to vSphere vMotion in that it allows a virtual guest to be moved between physical servers without any downtime or disruption to the end-user experience. Previously, migrations could only be achieved with quick migration where a guest was paused for the time it took to transfer memory between servers. It is worth noting that vMotion is not included in the free version of vSphere (Hypervisor).
Host Clustering uses Cluster Shared Volumes to vastly improve the ability to fail over individual guests between Hyper-V servers in a multi-node high availability configuration. Clustering is not available in the free version of vSphere.
I've mentioned that Hyper-V is built on or into Windows Server 2008. This platform has a long history, stretching back to the original release of Windows NT 3.1 in July 1983. In fact, the latest versions of Microsofts operating systems (Windows 7 & Windows 2008 R2) are designated as release 6.1 using the same numbering system.
The first releases of Windows NT were notoriously poor on the breadth of hardware they supported. Drivers for the desktop versions of Windows were not compatible and consequently only a limited range of hardware would run under NT.
At the time this had the benefit of providing driver stability, a key requirement of any server platform. Since then, the range of supported devices and drivers has widened significantly. Consequently, Windows 2008 (and therefore Hyper-V) supports a huge range of hardware components.
This is in contrast to vSphere, where the Hardware Compatibility Guide is quite restricted. Clearly parallels can be drawn with Microsofts desire to ensure early versions of Windows NT were stable.
One good example of a supported feature is MPIO (multi-path I/O) for storage. MPIO is available natively within Windows 2008 for iSCSI and Fibre Channel devices. However, VMware was required to implement a new API (vStorage API for Multipathing) and Pluggable Storage Architecture to provide multipathing features.
In conjunction with the benefits of support are those of management. Companies looking to virtualize their x86 platforms will already be familiar with the deployment and maintenance of Windows Server, as this will already be their choice of platform today. Even in organizations where Unix variants are in the majority, Windows will likely be used on the desktop or for email services.
This means companies have a degree of skill and maturity in managing Windows environments. This extends past the simple installation process and covers patch management, security, upgrades, monitoring and reporting. For example, all of the Hyper-V features can be monitored and managed using WMI, the standard Microsoft Management Framework.
The vSphere hypervisor is based on a Linux kernel and so administered through a mixture of the command line and GUI client. Deploying vSphere requires training of workers on a totally new platform, with new concepts and terminology.
vSphere will require integration into existing management frameworks and the customization of maintenance and upgrade procedures. While the cost of training may seem low, for each person trained it represents the equivalent of a single vSphere license.
Virtualization, Going Forward
As previously discussed, VMware is the clear leader in server virtualization. vSphere is more mature than Hyper-V in many respects, yet not all users need the advanced features provided by VMware. Where users are starting their virtualization journey, Hyper-V may provide a more logical choice because:
The product is offered free, or bundled within existing Windows 2008 purchases.
Hyper-V uses Windows 2008 Server, which already had wide support and skills within many organizations.
Hyper-V leverages Windows 2008 Server components, providing support across a wide range of hardware.
Hyper-V can therefore be suited to many virtualization requirements. However, it is probably fair to say that it currently cant meet high performance, large-scale deployments. VMware still has the edge in networking and security (with features such as vShield and vDS (vNetwork Distributed Switch), but these advanced features are not needed by all clients.
Microsoft will continue to improve and add to Hyper-V. Based on previous history, they will probably continue to give the product away or bundle it for free within the existing Windows Server platform in order to gain market share.
Ultimately, VMware has to make money from vSphere as their core business is virtualization. For Microsoft, virtualization today doesnt represent their core business but is a stepping-stone to moving customer computing workloads into the cloud. They can therefore continue to provide Hyper-V at no cost. And over time, as the feature differences disappear, the definition of good enough will meet most customers requirements.