Posted by: S R Balasubramanian
cost-benefit analysis, data center power and cooling, power consumption, server virtualization
In my previous post, I tried to demystify server virtualization and made up a case for considering this technology for use as it helps optimize resources. For those who are first time users, doubts arise about its efficacy and its real benefit. Any IT investment proposal, such as in virtualization, has to be supported with a cost-benefit analysis so that it is approved by business.
Benefits are real; I have experienced them. How much we gain will depend on the mileage that we extract from technology and our propensity to try and innovate. Let me explain various benefits that virtualization can bring in. Following are the key areas where we can see gains:
1. Better utilization of hardware resources:
You can subdivide the processor and assign more than one application to it. For instance, I have often run four different applications running under different OSes, assigning them to a single processor. In the normal course, processors may be fully loaded or partially loaded and therefore we have server resources that lie idle and when we count total idle capacity in various servers, we may find a huge unutilized capacity. Since virtualization creates a pool, we can assign desired resources to each application.
2. Minimum physical space required:
Since we utilize fewer servers the space requirement in the data center comes down drastically if servers are stacked in a rack. In these days when space is at a premium, virtualization comes as a boon to us.
3. Lower power consumption:
Since we use fewer servers, the consumption of power would be low, despite the processors being loaded fully. That reduces the amount of heat generated by servers, and correspondingly, even the power consumed by air conditioning systems is also lower. In one of our recent implementations, we proved that the power consumption could be lowered by 40% with virtualization implementation.
4. Lower investment (capex) on hardware:
Proper capacity planning could see a drastic reduction in the capital expenditure that we incur on server buying. For instance, we had blade servers and by creating a pool across several blades we were able to use the available resources and thus put away the investment proposal that was on my desk. In case we host our applications or use external resources, expenses would come down.
5. Less maintenance overhead of IT:
Virtualization simplifies server management as the entire server farm can be managed through a single console. In addition, recurring expenses on AMC and other costs reduce.
6. Provision of resources on demand:
In a conventional environment, since we dedicate a server for each application, we are at our wit’s end when we have to make available sever resources for any urgent requirement. In a virtualized environment, we can make available additional resources on demand from the pool we create. In additional we can cater to a periodic demand (say month end or year-end processing0 by reducing the resource allocation to any non-critical application and make it available temporarily to the ERP or any mission critical run.
7. Easier to do patch management and upgrade:
We used to create a clone of a server and apply patches on the original file. If for some reason, the new version did not run, we could revert to the old version within minutes. The same process applied to software version upgrades and this was a great facility which made these tasks easier.
8. Disaster recovery planning:
Various features exist through which you can recover fast in case of any interruption due to hardware failure. The entire set of programs can be backed up on a different physical server and can be activated quickly.
How to convince the management
These benefits are ones that I was able to enjoy and once implemented we went about quantifying some of the benefits and demonstrating them to the management. The one question that I am often asked is: How did I justify the investment to the management at the time of taking approval?
I, of course, had problems in working out a cost-benefit; and therefore took a different stand. I worked out figures showing investment that we would otherwise make on additional servers if we did not go in for virtualization: that figure being much higher than the investment in virtualization. It worked and I got the required approvals.