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This is part two of a two-part article. Part one was published last Friday.

Application performance

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 virtualisation is reduced network utilisation. “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 per cent to 10 per cent.

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 virtualisation 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. Labour costs associated with provisioning have therefore dropped 80 per cent.

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, virtualisation 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.

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 data centre. I’d like to be able to manage the whole infrastructure with one server,” he says.

Computer Sciences (CSC) also found that backing up virtualised 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 virtualisation 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 virtualisation, 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 data centre consolidation, virtualisation 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.”

Next Financial has made advanced business continuity affordable by replicating 11 physical servers at its primary site to three physical servers with 11 virtual machines at a collocation facility. Leftover processing power is used as a primary Web server and application server farm for sales force field applications. “It would have been very expensive to have a bunch of duplicate servers sitting there doing nothing most of the time,” Carlo says.

Arvato Mobile uses Virtuozzo to isolate multiple development environments on its servers, to prevent any one project from accidentally overwriting the files of the others. “We can also create a quick virtual backup so that if something goes wrong, it’s easy to roll back,” Arvato’s Loesche says.

And NewEnergy uses Solaris Containers to isolate and run hundreds of simultaneous Monte Carlo simulations across its Sun N1 Grid of Sun Fire X4100s with minimal need for software changes.

There’s little doubt that server virtualisation is poised for a promising future in the data centre. The technology works, the benefits are real, and the savings in server hardware and provisioning costs can be dramatic. For server virtualisation to really take off, however, migration and management tools will have to mature. In particular, remote management needs to be improved, and virtualisation standards need to be developed that will allow different virtual platforms to be managed together across the network. VMware has been working with AMD, Intel, and other hardware and software vendors to eventually deliver open standards, but the effort will no doubt take time. Nonetheless, for targeted implementations aimed at solving specific business or IT issues, server virtualisation makes a lot of sense today.