Server virtualization: Doing more with less

Although server virtualization technologies are still maturing, early customers see real benefits

Virtualization has gone mainstream. According to The Yankee Group’s 2006 Global Server Virtualization Survey of 750 businesses, 62 percent of respondents said they already had a virtualization solution in place or were in the process of migrating to one. Only 4 percent did not have plans to tap server virtualization.

Given the technology’s upside, it’s easy to see why. Server virtualization divides a physical server into multiple virtual machines, each of which can run its own isolated operating environment and applications. That means less hardware, reduced power and cooling costs, and extended datacenter life. The ability to provision a new server simply by loading a virtualized image onto existing hardware not only saves IT management budget, it makes the business more agile.

Make no mistake; commodity server virtualization is a relatively young technology. The market offers multiple solutions but few standards. Consensus among customers is that it works as advertised and is not difficult to implement, but efficient management and migration remain ongoing challenges. Nor is virtualization appropriate for every application. Applications that hog I/O and memory resources, such as large database deployments and Microsoft Exchange, often are not good candidates for sharing server hardware with other applications, even in a virtual environment (see “Virtualized databases: An alternative solution”).

Customers that have taken the plunge are typically in the early phases of virtualized infrastructure: After initial testing, applications are virtualized gradually as servers are retired, applications are upgraded, or IT moves toward a service-delivery model. Despite a cautious start, however, the common theme among these customers is great enthusiasm for the genuine benefits virtualization can bring.

A lot less hardware

One of the key incentives driving the market for virtualization is a desire to reduce costs associated with server hardware, both for limiting new purchases and reducing the total portfolio of equipment in the datacenter. For Capital One, a diversified global financial services company, virtualization provides a key component of a three-year IT consolidation strategy and transformation to an on-demand service delivery organization. This transformation is well into its second year.

“In the past, our businesses owned their server hardware and applications and had them configured to their individual specific requirements,” says Lee Congdon, managing vice president of corporate technology at Capital One. “The result was that we ended up with everything, including Unisys, Tandems, Suns, and AS/400s — you name it. On the software side, we were running Novell NetWare, old versions of [Windows] NT, and Windows 2000.”

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To tame this unwieldy environment, Capital One began using VMware ESX Server to pack multiple server environments on fewer, more powerful physical servers. Rather than dedicating servers to individual business units, business users are increasingly assigned smaller shares of more powerful processors. “We currently have about 150 server instances running on 17 physical servers,” Congdon says. And rather than giving each business its own applications, Capital One has consolidated to five IT-approved platforms. The business units simply buy services, such as knowledge or content management, and often don’t even know what platform they’re using.

Similarly, Citrix is in the early stages of consolidating 15 racks of 200 out-of-warranty servers to just two racks, or a total of 10 HP ProLiant DL585 four-way, dual-core Opteron servers, using Microsoft Virtual Server 2005 R2. “We’ll be saving $9,000 per month in power costs and huge amounts in network port and cabling costs,” says Dimitri Mundarain, Citrix’s manager of datacenter operations. Why Microsoft? “VMware’s ESX Server is more technically advanced and has a better management console but would be much more expensive in licensing and training costs. Our datacenter runs on Windows, and we like the fact that MS Virtual Server uses the same type of interface.”

For other organizations, virtualization is essential to extending the life of datacenters that are close to capacity. “We were running out of air- and power-conditioning capacity, which doesn’t scale and is very expensive to replace,” says Neal Tisdale, vice president of software development at NewEnergy Associates, a software and energy consulting company. NewEnergy used a combination of VMware GSX Server and Solaris Containers to consolidate its server hardware. The datacenter now runs 19 degrees cooler with no cooling upgrade, Tisdale says; and if the power fails, its batteries can keep it up for days, rather than hours, thanks to the reduced server power load.

Tisdale agrees that VMware is feature-rich but says NewEnergy didn’t need many of its features. “We didn’t want to drive up cost and complexity by throwing in a lot of enhancements like load balancing and VMotion,” he says. “We just wanted to get the heat savings quickly and easily.”

Packing them in

Hand in hand with hardware consolidation comes increased utilization of current server resources. Before virtualization, IT departments tended to limit each physical server to a single application and operating environment, as multiple applications tended to conflict with one another. The result was often server sprawl and inefficient use of server resources. Congdon says running multiple virtual operating environments on each server has increased server utilization at Capital One from an average of 30 percent to as much as 80 percent.

After monitoring his VMware environment for two weeks, NewEnergy’s Tisdale actually found that he could pack many more virtual servers onto a physical server than he originally thought — in the high teens and low twenties, rather than seven or nine. “Users generally overestimate how much they’re using a server, and the software vendors are conservative in estimating the memory needs of their applications,” he says.

Virtualization consumes its own server resources, of course, which can take its toll on application performance, but users point out that the overhead is offset by running applications on more powerful servers and taking advantage of VM portability. Congdon says general response times have improved now that his applications are sharing much more powerful server hardware.

When application performance declines due to an overburdened server, Next Financial, a securities broker/dealer, simply moves the virtual application environment to a less busy server. “You just shut down the virtual machine, move its disk on the SAN from one LUN to another on the SAN, reattach it on the new host, configure the VM, and launch,” says CTO Ismael Carlo. (The company isn’t using VMware’s VMotion management product, which can actually move VMs around on the fly without any downtime.)

Another side benefit of virtualization is reduced network utilization. “If two of those servers on the same box talk to each other a lot, you’re actually offloading network traffic,” says NewEnergy’s Tisdale, who claims that the performance gains from more powerful servers and virtual network connections overshadow VMware GSX Server’s overhead of 7 percent to 10 percent.

Provisioning a mixed bag

Managing a virtual environment is a two-sided picture. On the plus side, the ability to quickly provision new servers simply by loading virtual images onto existing hardware produces tremendous savings in IT staff time and resources, not to mention improved business agility.

For example, Mornay Van Der Walt, vice president and systems architect at Ixis Capital Markets, a global financial services company, estimates that virtualization has reduced the time it takes to provision a new server to as little as five hours in the virtual world, from as long as 17 days for procuring and building a new server in the physical world. Labor costs associated with provisioning have therefore dropped 80 percent.

Management savings can also come from upgrading to more capable servers. For example, NewEnergy’s Tisdale claims there were significant administrative cost savings from upgrading to higher-end servers with advanced lights-out management tools. And, of course, virtualization reduces the number of physical servers to monitor. Migrating existing applications and data from the physical to the virtual world is more of a mixed story, however.

Capital One’s Congdon used VMware’s P2VAssistant tools and found them to be sufficient. “There were very few technical migration issues,” he says, “though there were a few cases, particularly when we wanted a really clean installation, in which we ended up building the server instance and reinstalling the applications manually.”

Lukas Loesche, director of IT operations at German mobile content provider Arvato Mobile, had an even better experience with SWsoft’s Virtuozzo. “Virtuozzo 3.0 has a [physical-to-virtual] migration wizard that is absolutely flawless,” he says.

Other users, particularly those performing large-scale migrations, may find the initial provisioning phase challenging. One option is to turn to third-party migration tools, such as those from PlateSpin and LeoStream, which can automate large numbers of physical-to-virtual migrations over the network from a single console. Tisdale found PlateSpin’s automation tools to be a real time-saver, but Citrix’s Mundarain found that they did not work well for every application, and that even with these advanced tools there were situations in which he had to resort to rebuilding the operating system and applications from scratch.

Other users, particularly those performing large-scale migrations, may find the initial provisioning phase challenging. One option is to turn to third-party migration tools, such as those from PlateSpin and LeoStream , which can automate large numbers of physical-to-virtual migrations over the network from a single console. Tisdale found PlateSpin’s automation tools to be a real time-saver, but Citrix’s Mundarain found that they did not work well for every application, and that even with these advanced tools there were situations in which he had to resort to rebuilding the operating system and applications from scratch.

“Migration is definitely not a science by any means,” Mundarain says.

Management hurdles

Other issues arise when managing the virtual infrastructure itself. The management tools offered by the vendors tend to be works in progress. For example, Ixis’ Van Der Walt has found managing remote servers with VMware’s Virtual Center management platform to be problematic. “VMware is good at managing local infrastructure, but you usually have to have a VirtualCenter Server at each datacenter. I’d like to be able to manage the whole infrastructure with one server,” he says.

Computer Sciences Corp. (CSC) also found that backing up virtualized physical servers to tape had its challenges. “It came down to whether we should use traditional backup for each virtual server or use VMware’s tools to do the backup and back up virtual machines as files,” says John Macioci, partner and deputy CIO of CSC. The company found VMware’s tools to be overly complex and decided to settle on traditional backup solutions from Veritas, treating each virtual machine as an individual server. (Arvato’s Loesche, on the other hand, has high praise for Virtuozzo’s backup tools.)

And even when the physical server load is reduced, you still have all those virtual servers to monitor and patch. This is where host-based virtualization platforms, such as Solaris Containers or Virtuozzo, have advantages. “Since all the VM file systems are accessible from the hardware node, you can update them all with one small script,” Loesche says. The drawbacks, compared with hardware emulation systems such as VMware’s ESX Server and Microsoft’s Virtual Server 2005, are that you can’t mix different operating systems on one hardware node, and if a bug crashes the kernel, the entire server crashes.

In fact, hardware failure is a big issue with virtualization, as a single failed physical server can bring down all the resident virtual servers. The threat can be offset, however, by the ability to move a virtual machine to new server hardware quickly if you can detect imminent failures before they happen.

“You may see some performance degradation, but at least you can keep the processes running,” Congdon says. “Then you can add hardware back to the pool seamlessly without having to take all those applications down while you configure the new systems.”

Less obvious benefits

Aside from simple datacenter consolidation, virtualization can have a multitude of other benefits. For example, CSC uses VMware ESX Server and Solaris Containers to store and run multiple customer demonstration environments on a single physical server. “We store several versions of our ERP suites and have five or six instances of each for different client situations,” CSC’s Macioci says. “We simply turn them on and off when we need them and can run 15 to 20 different demo environments concurrently.”

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