Calculating the Mean Time Between Failures?

Blue Booger asks: "I was looking over some fibrechannel hard drives and noticed that the Mean Time Between Failures was rated at 1.2 million hours. I thought that was pretty high, and figured it up to be close to 137 YEARS!! I went to check some regular IDE drives just for comparison, and they were rated at 500,000 hours (57 years). Now, as I understand it, this is supposed to be the average time that you can expect the drive to last before failures. I rarely have an IDE drive last more than 4 years, and my record is 10 years, so what is the deal? BTW, that is 57 years running 24 hours a day...the MTBF is rated as power on time. Here you can find Western Digital's glossary that defines the term MTBF (pdf). Here you can find a spec sheet on one of their 20GB IDE drives. I checked, and Seagate also lists similar MTBFs. How the heck are they coming up with these numbers?"

Comments

Simple, it's called "lies"

[Anonymous Coward]

Sure, the test engineers sit and rub their chins and write numbers on paper and do stupid tests in the lab, but in the end it comes down to this:

• WD Guy 1 Hey, what's the MTBF for our new drive?
• WD Guy 2 Dunno, what's Maxtor saying?
• WD Guy 1 sez here "300,000" hours
• WD Guy 2 okay, ours is 500,000 then
• WD Guy 1 I smell a NEW VICE PRESIDENT

Re:As a sidenote

[NickDngr]

DISCLAIMER: The views expressed hereafter are not necessarily those of MENSA, which I am only a member of.

Shouldn't that be "The views expressed hereafter are not necessarily those of MENSA, of which I am only a member." I would think proper grammar usage would be a prerequisite for being a MENSA member.