One of the key benefits of server virtualisation is saving money (on average 10 to 15 per cent), writes Simon McKenna, virtualisation strategist at Fujitsu. But unless the project is properly scoped, it will be hard to prove the benefits, making further virtualisation harder to justify. The first phase should be to analyse what you have and what can be virtualised. Here are three key considerations in a successful virtualisation programme:

1. Is it right for you?

• Whereas the best time to virtualise a server is as part of a refresh, the worst time is when one has just been completed. Unless the physical server can be re-used, disposal of the release asset may have a negative impact on the return on investment.
• Consider where servers are, both physically and logically (on the network), and how your security policies enforce separation - there may not be enough servers in a location to make virtualisation a worthwhile task.
• Understand licensing and support - every software vendor has different policies for a virtual environment. Verify these and understand any cost or supportability before virtualising - traditional consolidation may be a better option.
• The business may have other plans for the server - it may be replaced, upgraded or retired, or considered too business-critical to be disturbed.

2. Understand the impact

Most significantly: networking, storage, backup and business continuity.

• The change that will occur in network architecture and traffic due to port consolidation needs to be considered.
• Virtualised servers are hosted on Storage Area Networks (SANs) rather than local disks within a physical server. This may have a significant effect on the capacity and performance required in the SAN.
• The storage and network consolidation can have a significant impact on backup. Additionally, virtual metadata needs to be managed.
• There are significant business continuity (BC) benefits to virtualisation, such as hardware abstraction and resource sharing. But the BC plan needs to be updated to ensure that the physical environment that hosts the virtualised environment is available.

3. Put control policies in place

• When granting access for administrators to the virtualisation management tools, ensure minimum required privileges are given to any individual administrator.
• Virtualisation makes provisioning a server easier, quicker and therefore cheaper. But there is a significant risk of virtual server sprawl. The justification for creating a virtual server should have the same rigour as ordering a physical one.
• Integrate virtualisation management into your existing processes rather than create it from scratch, then evolve these to leverage virtualisation benefits. This will prevent unnecessary duplication in people, processes and tools.