In my last post I touched briefly on a claim I’m hearing a lot in IT circles these days. This claim is often heard in discussions surrounding multi-hypervisor environments and most recently in VDI discussions. The claim in question, at its’ core, says this – “If you have two procedures to perform the same task you double your operational expense in performing that task”. Given the prevalence of this argument I wanted to focus on this in one post even though I’ve touched on it elsewhere.
As mentioned in my last post, Shawn Bass recently displayed this logic in a debate at VMworld. The example given is a company with a mixture of physical and virtual desktops. In this scenario they manage their physical desktops with Altiris/SCCM and use image-based management techniques for their non-persistent virtual desktops. Since you are using two different procedures to accomplish the same task (update desktops), it is claimed that you then “double” your operational expense.
As I’ve said, in many scenarios this is clearly false. The only way having two procedures “doubles” your operational cost is if both procedures require an equal amount of time/effort/training/etc. to implement and maintain. And the odd thing about this example is that it actually proves the opposite of what it claims. It’s very common for organizations to have physical desktops that they manage differently than their non-persistent virtual desktops. Are these organizations just not privy to the nuances of operational expenditures? I don’t think so, these organizations in many cases chose VDI at least in part for easier desktop management. For many, it’s just easier and much faster to maintain a small group of “golden images” rather than hundreds or thousands of individual images. So in this example adding the second procedure of image-based management can actually reduce the overall operational expense. Now a large portion of my desktops can be managed much more efficiently than they were before, this reduces the overall time and energy I spend managing my total desktops and thus, reduces my operational expense.
We see this same logic in a lot of multi-hypervisor discussions as well. “Two hypervisors, two ways of managing things, double the operational expense”. When done wrong, a multi-hypervisor environment can fall into this trap. However, before treating this logic as universally true you have to evaluate your own IT staff and workload requirements. Some workloads will be managed/backed up/recovered in a disaster/etc. differently than the rest of your infrastructure anyway, so putting these workloads on a separate hypervisor isn’t going to add to that expense. The management of the second hypervisor itself doesn’t necessarily “double” your cost as in many cases the knowledge your staff already possesses on how a hypervisor works in general can translate well into managing an alternate hypervisor. A lot more could be said here but in the end, CAPEX savings should override any nominal added OPEX expense or you’re doing it wrong.
In general, standardization and common management platforms are things every IT department should strive for. Like “best practice” recommendations from vendors, however, we don’t apply them universally. The main problem with this line of thinking is that it states a generalization as a universal truth and applies it to all situations while ignoring the subtle complexities of individual environments. In IT, it’s just not that easy.