Jon Bach, who runs Puget Custom Computers in Seattle, explains Why RAID is (usually) a Terrible Idea in his blog.
Breaks way more often than disks do Jon notes that for some reason many of his customers come to him convinced that they need RAID on their home or professional workstations, and he tries to talk them out of it, often with no success. I imagine the conversation goes like this:
CUSTOMER: I want to spend hundreds of dollars on RAID.
JON: Well, we build and service hundreds of computers each year and we don't recommend it.
CUSTOMER: Are you a communist? I want RAID. I want to spend the money. I want the hassle. I want the false sense of security. Give me RAID!
JON: Just to prove I'm a capitalist running dog I'll take your money. But I still don't recommend RAID.
CUSTOMER: Fine. Since we're on the subject, what is RAID?
OK, so why is a non-communist against RAID? Maybe because he's part of the reality-based world. As he notes in his post:
. . . I estimate that anywhere from 25% to 30% of our customers with RAID will call us at some point in the first year to report a degraded RAID array or problem directly resulting from their RAID configuration. Granted, a failed RAID1 array does not mean data loss, but it certainly means a long, frustrating hassle.
His judgement is that most customers are happier with regular backups and have way fewer problems. I'd amend that to better off with an automated offsite backup service like Carbonite or Mozy which are both set and forget.
What RAID doesn't protect you from Jon also notes that backups offer protection that RAID doesn't. Specifically, RAID can't help you with:
Where will Jon recommend RAID? For a desktop machine he allows that striping (RAID 0) may make sense if you know you are I/O bound in things like video editing. He also recommends that if you do go the RAID route, buy a quality RAID controller. He's found that Windows-based RAID software is prone to problems.
Jon isn't talking about server RAID But I will. If smart engineers did a clean-sheet storage design today, they wouldn't come up with today's RAID systems. That, however, is a topic for another time.
Comments welcome. If I can get an account on ZDnet, I'll even try to reply.