The server that wasn't

Agencies are exploring OS virtualization to get more out of their systems

[It] is simply a matter of virtualizing the file server and then copying it ... . You don't have to worry about buying a file server and setting it up.'

'Dennis Clem, Pentagon CIO

Somewhere deep inside the Pentagon is a football field-sized room filled with servers. But because the building is being renovated, all those machines must move elsewhere in the coming months. It's up to Dennis Clem, CIO of the Office of the Secretary of Defense and the Pentagon, to figure out where. And that's not an easy job.

'Space for data storage and file servers is a real issue across all of the Pentagon,' Clem said. 'The question is where do we put all that IT?'

Any technology that could help with the task gets Clem's attention. Virtualization, the ability to consolidate IT by running multiple virtual file servers on a single server, drew his particular interest.

Typically, Pentagon users dedicate an entire server to one application. If they bring in another application, it usually requires another server. As a result, few servers run at maximum capacity because many applications use only a portion of a server's resources. Virtualization enables one complete operating system, plus associated applications, to run within another. By running multiple instances of a server OS, the system is better utilized. And that's not all.

'It solves the space problem, and it reduces the cost of buying replacement hardware,' Clem said.

Why virtualize?

Virtualization gets a lot of ink in the trade press. And in fact, managed hosting providers or centers of excellence would be right to go ga-ga over the technology because they can do more with less. But virtualization presents even greater potential benefits, server consolidation being the most prevalent.

With the Office of Management and Budget insisting agencies consolidate operations wherever possible, virtualization offers an easy way of grouping together operations. As hard as an agency might try to standardize on one platform, applications written for alternate OSes inevitably crop up.

Virtualization eliminates the need to build separate machines for those apps'and that appeals to IT managers like Clem.

When he signed on at OSD, Clem was tasked with consolidating 14 different IT infrastructures from 17 organizations into a single enterprisewide system. One group had 127 servers, only five of which hosted more than one application.

'We are now consolidating all those servers into a much smaller number,' he said. Using VMware Server software from VMware Inc. of Palo Alto, Calif., Clem said he'll be able to trim 1,000 servers down to 239.

Virtualization could also keep alive an application written for an older OS. Legacy software running on, for instance, Microsoft Windows for Workgroups, could continue to run, unmodified, on a virtualized instance of that OS, thereby eliminating'or at least delaying'the need to port the program to a newer OS.

When the Federal Aviation Administration embarked on a program to update its traffic flow management system, the team used VMWare to run a flight scheduler program, written for HP-UX, on its new Red Hat Enterprise Linux environment, while a new version of the program was being written in Java.

'It got us out [the] door, and allowed us to continue with the modernization while the code was being redone,' said program manager Joshua Gustin.

Virtualization could also help with disaster recovery, allowing agencies to move instances of a running program to other locations should the need arise. With the right technology, a virtualized OS could be stopped and moved to another server within a matter of seconds'even if that server is located thousands of miles away.

'I want to distribute our architecture around the world,' Clem said. 'We have a lot of real estate. With the virtualization software it is simply a matter of virtualizing the file server and then copying it to wherever you want to be. You don't have to worry about buying a file server and setting it up.'

Finally, virtualization holds promise at the client level, where end users, such as analysts or engineers, could operate multiple platforms on a single system.

The next version of Novell Inc.'s SUSE Linux, due out this summer, will come with fully integrated virtualization capabilities based on open-source Xen virtualization software.

Through administration software, an end user or network admin could set up a virtual machine. You specify how much memory, hard drive space and other resources you want the virtual machine to consume.

Then after you configure the settings, you install the OS and applications you want the virtual machine to run. The management console then lets you start the new OS as you would any other program on the computer.

How it works

'Think of the virtual machine as an entire mini-computer,' said Justin Steinman, who does data center marketing for Provo, Utah-based Novell.

When considering virtualization technology, it's important to understand that different companies and open-source projects approach the matter differently.

VMware, for one, takes the most straightforward approach, employing simple software-based OS virtualization. Here, the virtualization software is installed on an existing server that allows that machine to run multiple instances of other OSes. Each OS operates normally, as if it has its own dedicated processor to do its bidding.

In the background, VMware emulates the processor. Each time a virtual OS sends a request to a CPU, the virtualization software rewrites the request before passing it along to the actual processor, balancing the request against those of other virtual machines.

'Every time the guest OS transmits a packet, it thinks it's talking with the physical hardware,' said Donald Becker, chief scientist at Scyld Software of Annapolis, Md., during a presentation he gave at a D.C. Beowulf Users Group meeting.

With this approach, you don't need to modify the host operating system. Simply install the software and you're ready to go. This allows VMware to host a version of Microsoft Windows on Linux, or vice versa, making for a cross-platform feature few other virtualization products offer. (Microsoft Corp. takes a similar approach with its Virtual Server, but it only works with various versions of Microsoft Windows.)

The downside to this virtualization model is that, depending on the type of work being done, the guest OS can operate slower than it would with its own processor. Dan Chu, VMware's director of developer and independent software vendor products, said the lag time can vary depending on the type of work being done.

Experts generally agree the more input/output a virtual OS handles, the slower it will run, since it must compete more for physical resources such as network interconnects. Industry estimates range from a few percent to 95 percent performance degradation.

Another approach gaining traction is something called paravirtualization, which the Xen technology is based on. XenSource Inc. of Palo Alto, Calif., is home to the Xen project and offers a commercially supported version of the software.

With Xen, the guest OS does need to be modified, usually through the addition of a module in the OS kernel. (The Xen development community has submitted a patch for possible inclusion in the 2.6 Linux kernel, according to Simon Crosby, chief technology officer for XenSource.) With this approach, the paravirtualization software offers an alternative set of system calls that can be accessed directly by the guest OS. The advantage of this approach is that performance can be a lot better'by as much as 95 to 100 percent of a dedicated machine.

Paravirtualization 'is extremely more efficient than changing the instruction stream to emulate the physical hardware,' Becker said. But because modifications are required, no paravirtualization software yet works with Microsoft Windows.

Kernel control

Although these two approaches are the most common, other companies take different tacks. SWsoft Inc. of Herndon, Va., for instance, uses a single OS kernel on each machine, but sets up multiple partitions for guest OSes. In this case, all the guests use the same kernel and applications. But they appear as distinct entities to end users, said SWsoft CEO Serguei Beloussov.

Although Unix itself was designed to accommodate multiple accounts, the virtualized approach is a lot simpler to administrate for large and complex sets of users, Beloussov said. And like paravirtualization, the performance hit is very low.

With so much buzz surrounding virtualization, the IT manager has to ask if it's ready for enterprise use. On an individual project basis, virtualization may work fine, but can it play a role across an agency? So far, the jury is still out.

'FEMA is not currently using [office information system] virtualization,' said Barry West, outgoing CIO of the Federal Emergency Management Agency (he'll start as CIO of Commerce next month). 'Virtual has some exciting features, but virtualization products need to demonstrate scalability, speed, ease of use, and cost-effectiveness before they become viable options for enterprise systems.'

'I'm not really sure we will go there,' FAA's Gustin said. 'There is potential in our modernization effort to do it, but at this point we really don't have a need.'

Linux distribution companies are looking to make virtualization more a feature than a service. Both Novell and Red Hat Inc. of Raleigh, N.C., plan to have Xen in their next enterprise Linux distributions.

'We're trying to think of it as more of an integrated solution,' said Brain Stevens, chief technology officer for Red Hat. 'Today, if you want to do virtualization, you usually buy a multitude of products and try to put them all together. We're trying to move it to be more of an integrated solution, so when you do an install [of a Red Hat OS], your system can be completely virtualized.'

Virtualization standards

One sign that the technology is headed towards the enterprise is its adoption by Dell Inc. of Round Rock, Texas. At the recent LinuxWorld conference in Boston, Dell CTO Kevin Kettle showed attendees how Microsoft Windows could be virtualized within Linux.

Never one to put its customers on the bleeding edge of technology, Dell is nevertheless bullish on rolling virtualization into data center systems management software. The company has integrated VMware ESX Server with the company's own systems management tool, OpenManage.

With the pairing, when OpenManage detects that a server is underperfroming'due, say, to a faulty fan or degrading drive'the software can migrate the virtual machines to another server without incurring any downtime.

In addition to working with OpenManage, the company is encouraging other systems management software vendors to develop a set of virtualization standards, regardless of system management software.

Said Jim Porter, senior manager in Dell's enterprise marketing organization, 'You're seeing lots of good customer choice around virtualization. Some of the products are more mature than others but over time the customer will continue to have good choice.'

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