Can you ever have too much of a good thing? Server virtualisation fans are wildly enthusiastic, but even some true believers are worried about how quickly scads of virtual machines (VMs) are being added to corporate IT environments.
"We love VMware," said Tom Dugan, director of technical services at Recovery Networks, an outsourced business continuity provider in Philadelphia. Even so, he's worried about managing an ever-increasing sprawl of VMs.
Hypothetically, a company that had 10 physical servers one year ago might have dropped that number down to eight with virtualisation. But today, that company might now have 25 VMs running on those eight servers, Dugan said. The number of physical servers the company needs to manage has dropped by 20%, but the number of operating system instances has increased by 150%.
The reason for this growth, said Dugan, is simple: engineers and users are now used to the ease with which they can deploy a virtual machine. Application users continually ask for their own server. With virtualisation, engineers can easily accommodate those requests. Savvy users realise how easy it is to get dedicated server space, so, he said, the number of VMs keeps increasing.
Policies that call for using VMware first, rather than buying a new server, will increase the number of virtual machines in an organisation, said Patrick Lin, VMware's director of product management for datacentre platform products. According to VMware research, 90% of VMware users have applications running in production on VMware platforms; of those, 25% have policies stating that any new applications are deployed on virtual machines by default. "If it's not on a VM, [the requestors and IT department] have to justify it," Lin said.
At this point, virtualisation proponents don't consider VM sprawl a huge problem. Despite the meteoric rise of virtualisation in the datacentre, VMs still account for a very small percentage of total operating system instances in production today -- between 1% and 2%, analysts estimate.
Down the road, however, VM sprawl may be setting up virtualisation shops for management headaches, says Eric Vishria, vice president of marketing at Opsware, a company that provides server, network and asset management tools.
Virtualisation users like to boast that they can deploy a VM in minutes, compared to days or weeks for a new physical machine. The flip side of that coin is having to perform routine management tasks in that shortened span. "With all that flexibility, you can get a lot of operational complexity," Vishria said.
Far from leaving its users out to dry, VMware offers an extensive collection of tools to help manage the many VMs its software has spawned. In particular, VirtualCenter is a management suite that works with Virtual Infrastructure 3 and VMware Server platforms. VirtualCenter, currently in release two, allows administrators to provision virtual machines and optimise their performance and availability across multiple physical servers. Components within VirtualCenter include VMware Distributed Resource Scheduler (DRS), VMware High Availability (HA) and VMware VMotion.
But VirtualCenter by itself can only take you so far, said Opsware's Vishria. With VirtualCenter, for example, you may be able to deploy a "golden image" of a virtual machine to a server, but "it doesn't do anything to help you create that golden image in the first place," he said. "There's no company in the world that is dealing with a single golden image -- they have two hundred and they're changing all the time."
More complications are coming, because VMware's days are numbered for being the only game in town. "Five years down the road, it won't be an all-VMware world," said Steve Wilson, vice president of product marketing at Cassatt, which makes the Collage system automation platform. Citing Microsoft's Virtual Server, or Xen in Red Hat and Novell Linux environments, Wilson sees many choices becoming available for base-level virtualisation.
All this belies the need for management and automation applications that span the physical and virtual worlds, Wilson said. "There's this sense that everything will be virtualised and that you won't need to worry about [physical servers]." But like it or not, "there are still actual servers there," he said.
Cassatt Collage Cross Virtualization Manager, or XVM, aims to improve management by centralising system images, then monitoring virtual machines and the physical servers they run on for failure or degraded performance, explained Donna Scott, vice president and distinguished analyst at Gartner. If it detects one of those conditions, Collage can reportedly redeploy the VM to the most appropriate hardware under its jurisdiction.
Is automation the answer?
The use of virtualisation management platforms is still relatively rare in all but very large enterprises. Due to the lack of management tools, some users believe they need to slow down virtualisation deployments.
In some large shops, the bloom is already off the rose for virtualisation, said Scott. The shop that consolidated 1,000 physical servers down to 250 is "initially happy to reduce its hardware spend." Then, management issues creep up on them. "They realise that the labour on those 250 servers is just as great as when they had 1,000," he said.
Dugan does acknowledge that virtual machine management is getting problematic. "You won't find anyone who likes VMware more than me, but it's taken some time to figure out what the pain is," he said. "Until we figure out a new paradigm of how to manage from a virtual environment, we're getting by today because we know how to manage things physically."
This article originally appeared on SearchServerVirtualization.com.
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