Server consolidation, the process of reducing the number of physical servers in a data centre or server room by migrating applications from several different servers onto one physical server has become a lot more feasable with the advent of operating system virtualisation. The need to reduce energy usage and cut costs has made virualisation the new strategic goal of IT departments around the world. Many CIO, however, are still considering the benefits virtualisation has to offer. So what are the benefits of server consilidation or virtualisation?

Virtualisation Benefits

1. Energy Saving

Probably the benefit of virtualisation that is most prominent these days, given the world energy crisis, and global warming, is the huge reduction in energy consumption that results from consolidating your  physical servers into a virtual machines resulting running on  a much smaller number of physical servers.  The exact ratio of physical machines before consolidation to the number needed after consolidation will depend on the typical load of each target machine and your available hardware. Typically one does an infrastructure audit to plan which machines to virtualise and where which physical box will be used to host the virtual machines.  Part of this audit will be an estimate of the resulting power and space saving. It is estimated that your typical server runs at around 20% utilisation!

2. Data Centre Space Saving

A consequence of reducing the number of physical servers, or enabling your existing physical machines to run more operating system instances, is the reduction in space in your data centre. Data centre space can be expensive and virtualisation allows you to get more out of your exiting buildings. 

3. Shorter Infrastructure Provisioning Lead  Times

Once your infrastructure has been virtualised your IT infrastructure becomes a lot more flexible and responsive to your organisations needs. In the past, when a business unit needed a new server to run so custom developed or off-the-shelf software, leads times to provision the machine could take up to 4 weeks. This is typically due to the the lead time required to get the purchase order authorised, place the order and then the delivery lead time from your hardware vendor. Once the machine arrives, infrastructure then needs to load and commission it before it can start to deliver the software service for which it was purchased.

With virtualisation, servers can now be provisioned in minutes or hours rather than weeks. When your infrastructure is virtualised your plan will allow for some spare capacity in your environment to accommodate future growth. This spare capacity can be used to provide more resources to existing virtual machines should their loads grow over time and it will also allow for the provisioning of machines for internal-customer business units when requested.  Even better, when provisioning a new virtual server, use is made of templates which means that the server will already have the required service packs and other required, standard security features enables when it is bought on-line. Not only does this save your system-administrators time but also lowers risk of machines, which do not comply with corporate policy being deployed.

4. Easier Backup and Restore

Once your infrastructure is virtualised you enable a lot more capability in your data centre. One of these capabilities is the ability to provide higher level of  availability to your users. With virtualisation you are able to take consistent backups of live servers without having to take them offline. This requires proper setup and configuration of your disk sub-system , but this is carried out as part of your virtualisation migration plan. Because of the ability to take exact copies of the virtual machine image, you can quickly restore an  image from a backup in minutes rather than hours in the event of hardware failure on an existing piece of hardware.

To restore a virtual machine all you need to do is restore the image to a physical machine with spare capacity and launch the virtual server. In some cases of hardware failure, such as CPU fan failure,  you can even migrate the virtual instance without any loss of data and repair the faulty piece of hardware. Since the virtual machine runs on virtualised hardware you no longer need to worry about hardware compatibility when restoring your backup image, the host operating system provides a consistent set of virtual hardware interfaces to the virtual machine.

5. Easier Syncing of Test and Production Environments

In larger organisations there are policy and procedures in place in taking any software system changes live. First work is done in the dev environment, then taken to the test environment, which is supposed to be a replica of live, and once tested it is deployed into production. The same procedure is used for applying operating system patches or upgrading server software such as web or application servers. Keeping the environments in sync is usually a nightmare. It often happens that an application works perfectly in dev but not in test and live. In the worst case there is a performance issue or bug that cannot be replicated in the test environment no matter how hard your technicians try. Now with virtualisaiton this is much easier to manage. Since the dev, test and production environment are virtualised a single consistent image of the server software can be provided to each environment. If a problem exists in live which cannot be replicated in test, then a snapshot of live can be used to run tests against, eliminating any variables around inconsistent environments.