Andrew Hillier, CTO & co-founder of CiRBA gives DCM a checklist of the things not to do

As enterprises look to squeeze cost savings out of their IT infrastructure, CIOs and data centre managers alike are turning to server consolidation as a way to meet this objective.

Server consolidation projects are easy to justify financially, but that doesn't mean that they're easy to execute. From believing new hardware must be purchased, to thinking virtualisation is the only route to success, misconceptions cloud the route to true cost savings and a more efficient data centre. The following contains some of the most common mistakes made in server consolidation projects, with advice on how to avoid them.

Equating consolidation with hardware purchases
Consolidation doesn’t necessarily require expensive new hardware. Consolidation onto what you already own is a far more cost-effective approach, and in many cases, should be the first thing you consider. 

Looking at simple utilisation patterns
While utilization and capacity requirements are important factors in considering consolidation, utilization alone  tells you nothing about server compatibility or what the right things to virtualise are. Additionally, utilization analysis is often overly simplistic. Analysis should consider how servers spend most of their time, or even the time of day when they are the busiest. Server workload patterns usually show specific spikes and if you can find servers that spike at very different times of day, although average workload would suggest their workloads could not be combined, more sophisticated analysis would suggest they can.

Failing to consider non-technical constraints
Rapidly moving to consolidation and/or virtualisation and not considering non-technical factors can create issues. While it may be attractive to move applications onto the same physical server, by doing so you subject the applications to the influence of that one piece of hardware. If the applications have different service-level requirements or change windows then you will experience issues.

Acting on dated information
Consolidation analysis projects can be lengthy, and are often conducted by professional services firms,  culminating in a paper report at the end of the engagement. Considering the rate of change in many IT shops, it is critical to be acting on fresh information.

Broadcasting intent prior to gathering data
IT staff may consider consolidation as a negative or even a threat to their job, as some might perceive it as shrinking their influence or importance due to a reduction in what they are managing. It is not unheard of to have staff find ways to make servers busy during the analysis phase to “shape” the results. It is best to gather empirical information from the environment prior to engaging staff in interviews etc. that telegraph your intent.

Using virtualisation as the only strategy
Many think only of virtualisation when considering server consolidation.  Virtualisation is powerful and flexible but strategies such as application and OS stacking are often attractive because they do not add the overhead, licensing and complexity of virtualisation. Additionally, some servers and their applications simply do not suit virtualisation and would as a result be left out of scope.

Leaving database servers out of scope
I/O limitations mean that database servers are not good candidates for virtualisation. Database server sprawl is a major issue for many organisations and there are ways to reduce numbers significantly with the right consolidation analysis and action.

Leaving application servers out of scope
Application servers often go untouched in consolidation projects. With the right planning, application servers (J2EE environments and accompanying web servers which are usually drastically over provisioned) can be consolidated for big gains.

Leaving test/development environments out of scope
Development and test environments are often the worst offenders when it comes to hardware and software sprawl. They are also least sensitive to workload issues as they are not customer-facing. In many cases a significant number of database servers can be consolidated without any impact on productivity or utility.

Failure to look into the variables that affect ROI
There are many factors that contribute to the financial impact of consolidation. For example, consolidating database servers can result in significant cost savings because it is relatively easy to action. Consolidating complex applications that require significant testing can kill ROI because of the time and effort required. Ensure you are choosing the right targets.