I was fortunate enough during my many years in the military to have been assigned to fixed-base communications units, meaning it was only on rare occasions that I had to choke down those infamous MRE (meal, ready to eat) rations that the US military hands out to personnel deployed in the field. For those unfamiliar with them, an MRE is a big packet containing a full meal for one, typically with items like corned beef hash, freeze-dried fruit, crackers & jelly, and maybe an oatmeal cookie.
When MREs are handed out at meal time, everyone takes a look at what their particular packet contains and the inevitable trading begins: "Anyone wanna trade with me for my corned beef hash?" or "Hey! Did anybody get chicken ala king? I'll give you my tuna with noodles!" In the end, though, everyone just put Tabasco sauce on everything to make it edible, so it didn't matter what they got in the first place.
The bottom line was that nobody was happy with everything in their particular MRE packet, which brings me to the topic of converged infrastructure solutions.
Like MREs, converged infrastructure packages have something for everyone, but they're inevitably a compromise, trading off one benefit for another. Any single box that contains compute, storage and network hardware and software will include some key component that's not to your taste and that you would rather replace with something else. But unlike the MREs, it's not likely that you'll be able to swap the included storage array with one you prefer.
So just what is it about converged infrastructure solutions that people find attractive? Well, in no small measure it's because they're positioned by hardware vendors to their customers as a quick solution to deploying private cloud in their data center--the "cloud-in-a-box" solution. But when that same customer has already deployed scale-out commodity x86 server hardware, a common SAN/NAS infrastructure and virtualized 60% of their apps, what about the existing infrastructure isn't already cloud-ish?
In all likelihood, all that's missing are the proper tools to effectively manage storage and application availability, and to provide chargeback or showback capability on resource consumption.
So before jumping on converged infrastructure as the answer to all your cloud questions, take a look at your existing environment. Odds are it's already cloud-ready, and you won't get stuck with the tuna and noodle entree. I really hated that one.