The Idle Cycle Conundrum
November 15, 2011
One of the advantages of a private cloud architecture is the flexible pooling of resources that allows rapid change to match business demands. These resource pools adapt to the changing demands of existing services and allow for new services to be deployed rapidly. For these pools to maintain adequate performance, they must be designed to handle peak periods and this will also result in periods with idle cycles.
In a traditional IT environment there are two excellent examples: backup and email. Email will typically peak at the start of the day and remain constant for the remainder of the day, with smaller peaks possible at lunch and quit times. Many traditional backup systems do the heavy lifting at night to avoid performance hits on production applications. With a private cloud environment, these different applications would most likely be sharing the same physical resources, which would increase hardware utilization and decrease idle cycles. Even with these advantages, idle cycles will still occur, and, in many cases, will occur regularly, based on time of day, month or year. The question becomes what to do with these cycles.
One school of thought revolves around power management. The idea being that if the resource isn’t being utilized, you don’t want to pay to power it. Depending on hardware and software, this can be automated at a very granular level. Processors can reduce power, server components can cap and more. Additionally, with virtualization software it’s possible to consolidate workloads across physical resources during off periods and shut down unused physical resources, bringing them back online as needs increase. This saves on power, but there is another issue.
Powered on or not, your IT hardware depreciates. The dollar value of purchase is written off over time on corporate books, and, more importantly, the hardware itself ages. IT hardware is quickly surpassed and is jokingly outdated by the time you stand it up. Additionally, as hardware ages, the MTBF increases. Powering it down during off peak periods saves money, but that hardware is still wasting away without providing value.
With this in mind, the other school of thought is finding alternative uses for that hardware during idle periods. Rather than shutting systems down and saving power, utilize the resources for other tasks that don’t otherwise get done or could use additional resources. Depending on the hardware and software platform, this could be done at either the physical or virtual level, with virtual typically being the easiest.