As technical people who plan, build and migrate to customers to virtual infrastructure, the question of what consolidation ratio customers can expect is a interesting one. Consolidation ratios tend to be a mix of wishful thinking and real-life. In my old IT days, I heard one large high-tech company was able to achieve 30 to 1 consolidation ratios for their Windows infrastructure. My CIO at the time asked why can’t we do the same, imagine the savings!
Truth be told there is a lot to consolidation ratios. Microsoft claims customers in real-life get between 5 to 7 virtual machines per host. VMware will say “it depends” which is the right answer, though, I’m curious to see what their customers achieve on average.
There are many methods. I myself like to use the 10-25% rule. This rule means at any one time, 10-25% of your users are actively using the system. So, to calculate the “real-life” consolidation ratio, I take the peak of the top 25% of the hosts and then use the average for the remaining 75%. It’s worked well for me over the years, especially when planning for grid computing workloads.
How do you plan your consolidation ratio? Discuss…