Server virtualisation is rising in prominence as IT managers look to maximise the power and efficiency of their enterprise servers. Matthew Aslett reports.
Continued pressure on IT budgets in recent years has forced CIOs and IT directors to attempt to do more with less, and make better use of their existing technology investments. Little wonder then that server virtualisation, which enables a single physical server to be split up into multiple virtual servers, has risen in prominence as IT managers look to increase server utilisation levels and squeeze the maximum processing power out of their hardware.
Server virtualisation has long been practised on mainframes and RISC-based Unix servers, with vendors building virtualisation capabilities into both their hardware and software, but virtualisation software specialists such as VMware, SWsoft and erstwhile Connectix have ruled the commodity x86 server space.
The importance of these software vendors has risen, as the cost of commodity servers has come down while processing power has gone up, creating vast swathes of Intel and AMD-based servers running at a fraction of their potential due to poor utilisation rates.
In recent months, several new projects and initiatives have come to light as a response to the growing interest in virtualisation technologies. Not only is Microsoft bringing to market some of the technologies it acquired with Connectix, but Intel and AMD are working on virtualisation technologies of their own, while virtualisation functionality is also beginning to be included in the leading Linux distributions.
"It is a very good sign. No market is mature if there is no competition," says Richard Garsthagen, technical marketing manager, EMEA, at acknowledged x86 virtualisation market leader VMware, which is itself now a subsidiary of EMC since its acquisition in January 2004.
Richard Garsthagen, VMware technical marketing manager, EMEA
"In the old days people looked at VMware just as a tool for trouble-shooting and test and development, they did not see it as a strategy. The whole industry is really growing and that is why more vendors are jumping on the train."
As well as increased competition drawing more attention to the market, Garsthagen is also happy that at least some of the ongoing developments will complement the goals that VMware has been working on. "Intel is going to help us on this. We make virtualisation for the x86 platform, a platform that was not designed to do virtualisation," he says.
The technology that Garsthagen refers to is Intel's future chip-level virtualisation advancements, also known as Vanderpool and Silverdale, that will come to market as Intel Virtualisation Technology (VT) later this year.
VT is designed to solve the problem Garsthagen refers to, that Intel's processors were never designed to support server virtualisation. "The challenge you always face is where do you need this technology? It has always been previously used in high-end systems," says Alan Priestley, strategic marketing manager for Intel enterprise solutions, EMEA. "Technologies like VMware and Virtual Server, coming from Microsoft, are now enabling that on volume servers and desktops.
Alan Priestley, Intel enterprise solutions strategic marketing
"This [VT] does not negate the need for the products available today, it complements the products and makes them more robust," adds Priestley, noting that it will better enable virtualisation software to work with Windows and Linux on Intel's processors. "The challenge we face and VMware face is that those operating systems were written with the assumption they had total control of the processor," he says.
According to Priestley, the problem goes back to the memory protection model introduced with the 286 processors, which introduced 'ring levels' on the processor. Typically, the OS runs in core ring zero and the application in ring three.
"The virtual machine monitor has to run at ring zero so you either push the operating system up to ring one, which creates overheads, or the other option is to modify the operating system, and that is impractical to do," explains Priestley.
"Virtualisation Technology from Intel will effectively create a ring 'minus one'," he adds. "The operating system is now running where it is intended to run. You cannot do that in software, you can only do that in hardware."
Intel competitor, AMD, is also working on its own processor-level virtualisation technologies to get around this problem. Known as Pacifica, these technologies are expected to be included in the company's future single-and dual-core Opteron processors. "We are very closely working with AMD as well," notes Garsthagen.
VMware is not the only virtualisation software vendor working with either Intel or AMD, however, with open source start-up XenSource currently gaining a lot of traction with software and processor vendors alike via its Xen Hypervisor.
Xen was conceived at the University of Cambridge's Computer Laboratories, and in recent months has garnered the attention of some of the biggest names in IT including Intel, AMD, IBM, Hewlett-Packard, Novell and Red Hat.
While much of the support for Xen has so far come from infrastructure providers at the processor, server and operating system level, Crosby says the company is also looking to add application vendors to the list: for example running security or back-up applications in virtualised partitions.
"All the open source operating systems have been ported to Xen and we are aware of a project within Sun to get OpenSolaris onto Xen," he says. "Dell has expressed an interest; Veritas is very interested; HP is very interested."
Xen is different from the likes of VMware and SWsoft's virtualisation technologies for a number of reasons. First, it is open source; and second, it requires operating systems to be modified to run on it.
"XenSource was formed in response to people who wanted an open, ubiquitous, hypervisor product," says Crosby. "It has been very clear to our group in Cambridge that there is a right way to virtualise. It turns out there is a right way and a less efficient way to virtualise. The way Xen [virtualises] turns out by design to be a more efficient way."
That way is known as para-virtualisation, and requires the operating system to be ported to Xen, and compiled for the virtualisation technology, just as developers might compile an operating system for a specific processor.
"That is the change the folks that run the Linux kernel are working on," says Crosby, putting pay to suggestions that Xen will become part of the Linux operating system. "Xen is not part of Linux and never will be by mutual agreement," he adds, noting however, that the Xen Hypervisor will be included in the major Linux distributions, from Novell and Red Hat, along with Xen-capable Linux kernel code.
The advantage of the para-virtualisation approach, according to Crosby, is that it is much more efficient than current offerings from the likes of VMware. The disadvantage, of course, is that the approach relies on an operating system vendor that is inclined to modify its code.
"You have many different levels of virtualisation," says VMware's Garsthagen on Xen. "The key differentiator with their virtualisation concept is you need to have a modified operating system. If you look at our customer base, the main group of users is Windows customers. Xen cannot ever work with Windows, because it requires a modified operating system."
That may be the case today, but another benefit of processor developments from Intel and AMD will be the eradication of that disadvantage, according to Crosby. "VT-enabled processors give us a way to deal with unmodified operating systems and still give us the performance benefits we want," he says.
Increased performance will be one of the greatest benefits of the processor-side virtualisation technologies, according to the vendors involved, although details are at this stage thin on the ground.
"You still need software to do this and it is good that they want to work with us," says VMware's Garsthagen. "This technology is still in development but it will absolutely allow us to do more robust virtualisation. Doing it only in software limits the resources you can use.
Xen is not the only virtualisation technology that is expected to benefit from process-based advancements and mount a challenge to VMware, of course. Virtualisation software vendor SWsoft in November announced a beta version of its Virtuozzo virtual server software for Microsoft's Windows, counteracting Microsoft's move into the virtualisation space and increasing its challenge to VMware.
SWsoft has previously focused Virtuozzo on the Linux server space but has been working on a Windows port of the product since early 2003, shortly after Microsoft acquired rival Connectix. Microsoft too finally released the server-related fruits of that acquisition with the launch of Virtual Server 2005 in November 2004.
Another new vendor that emerged on the scene in February 2005 is Virtual Iron. Formerly known as Katana Technology, the company emerged from 'stealth mode' with its VFe technology, which has been under development since 2003 and combines the concepts of bare metal provisioning, server virtualisation, and clustering and grid technologies.
"We saw those three areas and we wanted to write a single environment that had the attributes of those three separate areas in a single environment," Virtual Iron founder and chief scientist, Alex Vasilevsky, says. "It is a virtual computing platform that is decoupled from the underlying computing infrastructure."
The company differentiates itself from virtual server suppliers such as VMware and SWsoft by the fact that its VFe technology enables the creation of virtual machines that span multiple servers and automatically handle workload management between them.
According to Virtual Iron, the building blocks for VFe are x86 processor-based hardware and Infiniband switching fabric. VFe installs the Virtual Iron Foundry layer directly on the hardware to create the virtual computing environment, which can span up to 16 physical servers and manage up to 128 virtual computers.
The technology will support Linux when it is generally available in the second quarter, with other operating systems due to be supported as and when they are demanded by customers. Support for 64-bit processors will also be added later in the year.
Vasilevsky dismisses the impact that the emergence of Xen could have on its plans to virtualise Linux environments, differentiating VFe from single server virtualisation technologies such as Xen and VMware's GSX Server and ESX Server products.
"It is two different technologies," he says. "That [VMware] is really taking a single server and carving it up. VMware is only virtual SMP within a single box. 'Virtual computers' carve up into virtual servers that span multiple servers at one time. Single server virtualisation we believe will commoditise in two years."
Two years might seem like a short time until commoditisation of the single server virtualisation space, especially given a recent survey of 75 US and 25 European CIOs completed by Merrill Lynch. Results showed that while 36% of respondents had invested in what Merrill referred to as 'virtualisation solutions,' 60% said they do not trust the technology enough for data centre usage: not just now, but for another two years.
Somewhat surprisingly, the virtualisation vendors do not dispute Merrill Lynch's figures. "I absolutely believe those numbers are in the right area, it is all about education," says VMware's Garsthagen.
"If you ask most customers today about virtualisation the number one thing they think of is consolidation.
That is a limited view of virtualisation. That is why a lot of customers today need to be educated about what other possibilities virtualisation brings, such as disaster recovery and high availability."
Garsthagen adds that he expects the delivery of x86 processor-based virtualisation technologies, as well as the associated server and software vendor backing, to increase that level of education.
Intel's Priestley agrees, adding that the simplification of the virtualisation infrastructure that these processor technologies will bring will also increase customer confidence in virtualisation. "One of the challenges the industry faces is if you use VMware and multiple versions of Windows and Linux and the application fails, where do you point the finger?" he says. "It is now more possible to run multiple operating systems on the same server; it is all about making better use of those servers."
Server virtualisation is already a hot topic for many IT directors as they try to make the best use of limited resources. The delivery of processor-based virtualisation from Intel and AMD will make it more convenient and cost effective to virtualise server environments, while XenSource and the likes of Virtual Iron are likely to keep VMware and its compatriots on their toes.