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.
Trouble ahead?
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.