Continuing on the theme of measuring Data Centre efficiency - power consumption of the facilities and IT load are only one element albeit a large one - that contributes to the overall efficiency of a data centre. Ultimately a DC has to deliver useful workload and the amount of workload that can be achieved within a given physical DC is an increasing challenge. Lowering server power and increasing the cooling effectiveness of a DC are one of several ways to enable more equipment to be installed into an existing facility.
General consensus seems to be that the servers in many data centres do not always run a maximum utilisation - many are in the 10-15% utilisation range. This results from many IT shops following a policy of hosting one workload ( application ) per server and sizing the server to support worse case usage of that workload - this leads to low average utilisation of the servers. There are several approaches that can be taken to increasing the server utilisation
Consolidating several applications onto the same server that have different mixes of utilisation - this is not perfect as a problem on one application could impact the others on that server causing significant business impact
Deploying virtualisation within the DC - this enables multiple OS/App instances to be run on the same server. There are multiple benefits here in that the server utilisation increases whilst the number of servers could potentially be decreased so reducing the overall electrical power consumption of the DC and consequently the utility bill. Another aspect of virtualisation is that to achieve the highest levels of consolidation it is best to deploy the latest generation high perf/low power servers, this can result in the removal of many older generation high power servers from the Data Centre and the deployment of a smaller number of newer more power efficient servers
There are circumstances where virtualisation may not be appropriate and it is necesseary to retain one workload per server - in this case an increase in the workload capacity of a DC can be achieved by replacement of older smaller servers with the latest generation high performance servers - this can enable the workload capacity of a DC to be significantly increased without building a new DC, again the side benefit here is that latest generation servers consume less power than the older servers they are replacing.
There are many different ways in which the workload capacity ( and hence utilisation ) of a DC can be increased , with care most can also result in a reduction in the electrical power consumed by the DC.
Given the right tools the utilisation of servers within a DC is 'relatively' easy to measure, so this element of DC effectiveness can be quantified. There is another major element that I believe contributes to the effectiveness of a DC - that is the processes that are in place to manage the DC and hence the way a DC can respond to the new challenges placed on it by a business unit. Gartner have an infrastructure maturity model that is useful to try and quantify how effective a DC is in responding to business needs and looks at responsiveness, Service Level Agreements, IT processes etc. Currently I do not believe many DC managers are measuring how effective their DC in terms of process and when asked to judge where they sit within a model like Gartner's many IT managers will judge themselves more efficient than they really are.
Are there other areas that contribute to the efficiency of a DC - I would be interested in your feedback.