Fellow blogger and cartoon writer Scott Adams writes in his Dilbert Blog posts about the [Monte Hall problem].Monte Hall was the host of the American game show Let's Make a Deal. Here is an excerpt:

"The set up is this. Game show host Monte Hall offers you three doors. One has a car behind it, which will be your prize if you guess that door. The other two doors have goats. In other words, you have a 1/3 chance of getting the car.

You pick a door, but before it is opened to reveal what is behind it, Monte opens one of the doors you did NOT choose, which he knows has a goat behind it. And he asks if you want to stick with your first choice or move to the other closed door. One of those two doors has a car behind it. Monte knows which one but you don’t."

Mathematically, on your initial choice of doors, you have a 1/3 chance of picking the car, and 2/3 chance ofpicking a goat. But, after you make a choice, Monte knows which door(s) have goats behind them, and selectsone that exposes the goat. If you stay with your initial choice, you still have a 1/3 chance that you win acar, but if you change your mind and choose the other door, your odds double, you have a 2/3 chance of winning.This is not obvious at all to most people, so Scott points people to the [Wikipedia entry] that provides the mathematicaldetails.

What does this have to do with storage?

When you pick a disk system, you are hoping you pick the door with the car. You want a disk system that meets your performance requirements for your particular workload and easy to deploy, configure and manage, with a low total cost of ownership for the three, four or five years you plan to use it.However, with over forty different storage vendors, there are some doors that might have goats. Some vendorshave only 90 day warranties for their software, and I don't know any customers that replace their disk systems that often.

(It was pointed out to me that it was unfair in my last week's post about[Xiotech'slow cost RAID brick], that I singled out EMC offering minuscule 90day warranties for the software needed to run their disk systems. I apologize. I have sincelearned that HDS and HP also shaft their clients with 90 day warranties. Apparently thereare a lot of vendors out there who lack confidence in the quality of their software!)

It would be nice if everyone published all of their performance benchmarks so that you canchoose the right door with the car behind it, but sadly in the storage industry, not everyoneparticipates with industry-standard benchmarks like the[Storage Performance Council].

In other cases, people make their choices based on past decisions. Perhaps someone beforethem chose one vendor over another, and it seems simple enough just to stay with the originalchoice. It is amazing how often people stay with their company's original choice, what we call in the industry the "incumbent vendor", without exploring alternatives.

So, if you bought an EMC, HDS or HP disk system in the last 90 days, it's not too late for you.Tell your local IBM rep that you are afraid you picked the door with the goat, and that you want to change your mind, and choose the other door and go with IBM instead.

You will double your chances of being happier with your new choice!

technorati tags: Scott Adams, Dilbert, Monte Hall, probability, 90-day, warranty, disk, system, benchmarks, SPC, SPC-1, SPC-2, game show, HDS, HP, IBM, goat, door, car