Seven things you need to do
Enterprises that seek a successful move to virtualisation have a number of hurdles to overcome;
and not all are obvious. Virtualisation offers much to the organisation that implements it
correctly—a reduction in power and cooling costs, fewer physical servers to manage, faster
go-to-market with new services, and easier, more effective administration of computing
workloads—but those improvements can be realised only when the process of virtualising your
mission-critical applications is managed appropriately. This paper identifies seven key things
that you must take into account if your business is to be successful in virtualising your
Introduction 1. Align virtualisation projects with business goals
Virtualisation—in the data centre, a storage Organisations that decide to virtualise do so for
system, or even on a personal computer—has a number of reasons. The “classic” reasons
become a major IT trend. Virtualisation software are generally:
separates the physical from the logical in an Less hardware to maintain by consolidating
IT environment, enabling a single physical multiple physical systems to virtual machines
computing resource to function as multiple virtual on fewer physical systems
resources. As virtualisation technology becomes Reduced costs for power, cooling, management
more mature, the conversation is moving from and provisioning
whether virtualisation should be used, towards Greater flexibility in assigning physical
the when and the how. resources to workloads
• Higher levels of uptime with fewer single
The process of introducing virtualisation into a points of failure in the environment
data centre can be daunting. Deciding which of
your applications to virtualise, and how best to Yet these “classic” reasons for virtualisation are
do so, requires careful planning and execution. not quite the “right” ones. While important, they
Properly managing and monitoring workloads don't capture virtualisation’s real potential for
once they are virtualised, requires specialised achieving business goals, which should always
tools. It's all too easy for virtualisation to be your primary priority.
reduce—rather than enhance—the operational
flexibility of IT. With the right tools and techniques, virtualisation
can be a catalyst for levels of automation not
This paper identifies seven key tactics for otherwise seen in the IT environment. By creating
successful virtualisation of your mission-critical workload templates and automating actions
1 applications. across swathes of workloads, you can substantially
lower the marginal cost associated with the To manage the cost of your virtualisation project,
creation of new services. Above all, virtualisation’s it's critical to get the volume and architecture
separation of the logical from the physical of storage right.
transforms IT's agility, making it much more able Anticipated growth of server and service
to respond rapidly to the changing needs of needs. Virtualisation’s ability to quickly create
business. Businesses that declare success in their new servers and services from templates can
virtualisation projects do so when virtualisation lead to virtual machine sprawl. Planning for
augments the processing of business. this growth, and creating policies and governance
to prevent uncontrolled server/service growth,
2. Create a full inventory is critical to a successful virtualisation strategy.
Once you have a virtualisation strategy in place, System management tools and their capabilities.
the first step—before any technology rollout—is It's likely that not all assets will be virtualised,
a full inventory of your environment. An effective so it's worth knowing what, if any, tools you
inventory must include, at minimum: have for monitoring and managing virtual and
• Server composition, location, networking physical assets as an integrated whole.
and peripherals. You can't determine your
hardware needs for virtual hosts without 3. Monitor pre-virtualisation performance
understanding the capabilities of your existing If you host multiple virtual machines on a single
assets. Location information is important host, they must share its resources; so if one
because virtualisation environments are highly machine oversubscribes processing resources, it's
centralised, so some services may need to be likely to affect others on the same host, resulting
relocated to be virtualised. Peripheral inventory in a reduction in quality for multiple IT services.
is critical because many virtualisation solutions Because of this heightened potential for multiple
do not support certain types of peripherals. failures, understanding the performance of virtu-
• Server workload and installed software or alisation candidates and identifying those with
services. The business services you plan to unusual needs is an important step in ensuring
host atop your virtual machines, along with virtualisation success. Although hundreds of
their needs for interconnectedness, will performance metrics are available, here are the
determine how they are positioned in the ones that are truly necessary to gather the gross
virtual environment. resource requirements of a virtualisation candidate:
OS and application licences. Processor time. This measures the percentage
Because virtualisation changes the terms for of time a processor performs productive work.
many types of software licences (some licence If a service requires large amounts of processor
costs will go up, some down), deciding what time, it may be difficult to collocate it with others
services to virtualise requires an accurate on a virtual host.
understanding of existing licences. Processor queue length. If a processor cannot
• Server performance baseline. Only by keep up with its load, instructions queue up for
understanding the current performance of a its attention. A high processor queue length
physical server can you make an educated can indicate that the workload needs more
decision about its virtualisation potential. Getting processing power.
this data can be hard, with native tools such as Total and available memory. Virtual systems
Microsoft Windows’ PerfMon being difficult to can assign memory to services on demand, so
use. This is the most critical inventory activity, identifying unused memory will enable you to trim
discussed in more detail in the next section. configurations to use memory more efficiently.
Current and anticipated storage requirements. Memory page rate. This indicates how much
Moving from segregated, direct-attached storage memory is being swapped out of high-performing
to consolidated storage requires significant RAM to low-performing disk. When available
2 investment in technology upgrades. memory is low and the page rate is high, it can
mean that the server’s memory needs are backup and restore, disaster recovery, snapshotting
greater than its available memory. and many other processes can sometimes be
• Disk queue length. Virtualisation solutions can more valuable than the benefits of consolidation.
have heavy requirements for disk performance Where this is the case, it can be valuable to
in order to process changes within the virtual locate a single high-use server on a virtual host.
machine. If a candidate workload has a high In fact, a consolidation ratio approaching 1:1 can
disk queue length, a bottleneck may exist with be an acceptable goal for deployment. So take a
its disk subsystem. hard look at the business benefits associated
• Thread context switch rate. Each process is with virtualisation. To help you determine the
made up of a number of threads, and a processor right consolidation ratio, consider the use of
switches between them (context switching) to monitoring tools that analyse data across multiple
process them simultaneously. A high context servers, since these can provide guidance as to
switch rate means that many threads are vying their ultimate destination and configuration.
for processor attention.
5. Right-size virtual resources to workload needs
While these measures help to identify physical IT environments today often over-engineer their
servers that may not be good candidates for physical servers because it is inexpensive to do
virtualisation, it's important to note that these so and ensures that machines have similar
counters are designed to measure entire-server physical characteristics. But this practice makes
performance only. To maximise your chances of little sense if your goal is to use hardware more
creating a high-quality virtualisation environment efficiently through virtualisation. Instead, you
that supports only suitable services, you should need to fine-tune assigned physical resources to
also measure the performance of individual the needs of your virtualised workloads.
applications and business services. For many virtualisation solutions, doing this with
native tools ranges from difficult to operationally
unfeasible. Measuring resource needs from
within a virtual machine does not accurately
portray those needs from a physical standpoint.
And the tools at the virtual host layer often can’t
dig far enough into virtual machine configurations
to provide actionable information.
To avoid a costly mismatch between assigned
resources and virtual machine needs, you need
tools that can look at individual processes within
virtual machines, compare that information with
data seen at the virtual host layer, and analyse
current and historical data to illuminate where
This sample report shows data used to determine strong
resources may be incorrectly assigned.
candidates for virtualisation using key performance
indicators such as processor and network utilisation,
average disk utilisation and the top processes
6. Decouple hypervisors from their
If you manage a virtualisation solution using
4. Think beyond consolidation
only the tools provided by its vendor, you'll
If you're virtualising only to consolidate hardware,
usually need a different tool for each
you may dismiss servers as candidates due to
management action. For example, administering
high resource use. But virtualisation has many
configurations within a virtual machine will
more benefits than consolidation. Improvements in