Virtual Servers Update: VMware vs. Microsoft vs. Xen

What a difference a year makes with the whirlwind of the server virtualization world. New cross-platform management tools, embedded hypervisors, wider acceptance of open source methods, protocols, standards, and simplified pricing have all made virtualization much more popular with IT managers.

While the market is growing, it still represents a minor portion of the entire server marketplace – less than 10 percent, according to Microsoft representatives. What is new is that virtual machine (VM) server technology is now available and more attractive to mid-tier users for four reasons:

• The free versions are more capable.

• Prices are coming down.

• Ease of setup and management is increasing.

• The technology can help reduce power and cooling requirements just as being green is gaining traction.

Nevertheless, virtual servers are just one part of the entire virtualization market, which is growing to include all kinds of computing, from storage virtualization to streaming applications installation, to virtual desktops.

But in the past year, four trends are obvious:

1) Growth of the hypervisor: The hypervisor is now found in more places, both exploited in the latest processor chips from Intel’s Virtualization Technology vPro and AMD-V, and as a standard package with most of the popular Linux distributions and soon for Solaris too. The hypervisors, or virtual machine control programs, for the three major vendors (Microsoft, Citrix and VMware) now support this embedded hardware, which makes for simplified installation and nearly one-button booting of virtual servers. And VMware has begun selling ESXi, a specialized embedded version that will begin shipping on servers imminently. HP’s ProLiant servers now offer built-in support for Citrix’ XenServer; older ProLiants can be upgraded too.

2) Interoperability: Interoperability has taken root, and we have seen in the past year a series of initiatives to make managing multiple VM vendors more palatable. Novell’s ZenWorks VM Manager and Orchestrator products are just from one of many products that will offer a way to manage more than one vendor’s hypervisor. Microsoft’s SystemCenter, CA and others have announced plans to support both Microsoft’s and VMware hypervisors, and Novell will also support Citrix’s solution too. VMware announced several management tools that enable automation of the entire lifecycle of a VM, including staging the migration from a development/test environment into production, according to Bogomil Balkansky, the Senior Director of Product Marketing for the company. “Our customers tend to want to do more with virtual servers once they get it into their shops.”

Another dimension to the interoperability story is a standards effort called the open VM format that is first expected to be finished sometime early summer. “With this format, organizations can use a standard set of VM management metadata to manage VMs running on different hypervisors. This architecture is fully extensible, allowing VMs to advertise custom configuration information, such as a virtual barcode, security requirements, or service level requirements,” says Chris Wolf, a senior analyst with the Burton Group.

“While work remains, the eventual goal of these standards is to provide hypervisor interoperability, such as by taking a VM image built on the Microsoft Hyper-V hypervisor and running it on a Citrix XenServer hypervisor without having to modify the VM’s configuration.”

And as another example of increased manageability, inventory and asset management vendors such as BDNA have tools that can account for individual VMs that are hosted on virtual servers when they discover server resources across an enterprise. “This is a strong sign that the market is maturing and that customers have a choice,” says Simon Crosby, the co-founder of XenSource and now the CTO of the division for Citrix.

3) Falling Prices and Improved Functionality: Prices are coming down and functionality for even the free versions is improving. The free products – and indeed, all of Microsoft’s virtual server line – continue to be a great way for enterprises to become familiar with VM technology and to do any evaluations before deploying them into production. Most noticeably Microsoft has announced they will expand their product line with Hyper-V, which will be included in all 64-bit versions of its Windows Server 2008, expected in August. Hyper-V ups the ante considerably, with support for symmetrical multi-processors and larger memory support.

On the paid products, XenServer continues to be the lower-priced spread, offering single-CPU versions and better value when compared to VMware. The latter’s prices are now almost comprehendible, an improvement from their obscure complexity of last year. VMware also introduced support for 10 gigabit Ethernet networks and larger memory and disk support with its latest version, and now has more than 700 pre-built virtual “appliances” or virtual disk images that are available as well.

Citrix hasn’t stood still either, and boosted the performance of XenServer since acquiring the company last year, especially when it comes to XenServer working with the company’s flagship Presentation Server product line. “We recognize that our customers want to run both products to solve dynamic data center problems,” says Crosby.

4) Widening Channels: The virtual server channel continues to widen, with more partnerships, agreements, and expertise than ever before. As smaller, specialty companies enter this market, they are looking to cement relationships, expand distribution, and make just about every component in the data center virtualized. “All of the services that do hardware and applications failover, disaster recovery, chargeback, and security will be built into hypervisors and run on VMs,” says Susan Davis, the VP of marketing for Egenera, one of the newer specialty virtual software vendors.

“This year is shaping up to be one of the most interesting years ever in enterprise IT infrastructure,” says Crosby.

Table: Virtual Server product comparison

*While Microsoft’s offering doesn’t have an embedded hypervisor, it does recognize and take advantage of computers with either the AMD or Intel virtualization chipsets.