"Mr Hard Drive" on Large Drives and Defragmentation

Do you need to defrag large hard drives? This was a question posed in "Security Now!" to Steve Gibson, the author of Spinrite and an expert on hard drives and data recovery. Here is the transcript:
Leo: Last question, from Pierre in Canada. Pierre wonders about the wisdom of defragging today's huge hard drives: Hi, Steve. This week a colleague told me about an article I then read on the Internet and asked me what I thought about it. I wasn't sure what to answer him because the article seems to make so much sense. So I thought, hmm, who would know better than the maker of SpinRite? What we're wondering is, according to this article, with hard drives getting bigger and bigger, defragging could have more negative impact on the drive than positive impact.
The two arguments are that, first of all, with a drive of, say, 500 gigs or a terabyte, the time it takes is getting so long, that's a lot of work on a drive for a very long period of time. The stress could reduce the lifetime of the drive. Secondly, hard drive transfer rates are getting so fast that the gain is not significant. Why bother to defrag a drive if you don't need to? So what do you think about this? Good job with SpinRite. I'm a programmer working in an IT department. We use SpinRite every day. Wow.

Steve: Well, that's an interesting question. One of the things that we learned with SpinRite 6, when I first incorporated real-time S.M.A.R.T. monitoring, where SpinRite is periodically polling the drive's S.M.A.R.T. data, one of the things SpinRite shows and watches is drive temperature. And we learned that a lot of drives, especially laptop drives, easily get overheated. Many people have had SpinRite stop, as it will, and warn them that their laptop drive is now at the manufacturer's upper limit of temperature. And sometimes this even happens with people who have desktop machines. Sometimes desktop machines that were designed for an earlier generation, smaller, and less power-hungry drive, people will add a drive to the existing enclosure or replace a smaller drive with a bigger one, which may draw more power and generate more heat. So the ventilation, which was adequate for the cooler drive, isn't for the hotter, more power-hungry drive. We've seen that a lot. So the only real downside I can see is you really want to make sure that your drive is not overheating. Unfortunately it's not easy to tell that. I mean, SpinRite has it built in, but defragging programs don't.
The other thing is, I would, if the question is I'm worried that defragging the drive might cause it to fail, then my reaction is, whoa, you absolutely want to solve that problem first. That is, one way or another you want to be in a situation where a drive failing cannot really hurt you badly. Which means you either backup enough; or you've got a RAID configuration so you've got some redundancy, so if a drive dies you're able to survive that. Because, believe me, I mean, I'm in the business. Drives do die. SpinRite can fix a lot of them; but, you know, sometimes when the heads fall off or they seize up or they burn out or something happens mechanically, there's nothing any software could possibly do. So...

Leo: Do you think you need to defrag drives these days? Is the speed sufficient that it's not worth it?

Steve: Well, it's interesting, the...

Leo: [Indiscernible] time is always going to be an issue; isn't it?

Steve: The transfer rates have gone up, but the hunger for data, I think, has gone up just as fast, if not faster, than the transfer rates. I mean, our systems don't feel particularly faster than they used to. I mean, when Windows 7 boots up in less agonizingly long time than Vista, it's like, wow, that's faster. But we used to turn our machines on, and they were booted by the time the CRTs warmed up. Those days are long gone. So my sense is that drives are faster, but everything is bigger. And so the bigness is completely offsetting the increase in data transfer rate. I still defrag.

Leo: You do. How often?

Steve: I don't do it fanatically. I saw that my defragger was running, that is, the services, I've got two services that run with the third-party defragger that I'm using. And I thought, oh, that's dumb, and I went and manually turned them off. But it reminded me that I hadn't defragged in a long time. My routine is, when I'm - I'm running a RAID, so I've got redundancy all the time. But every so often I want to take a snapshot. So what I'll do is I'll just go through a housecleaning. I will empty caches. I'll look at the size of my - I'll sort by file sizes, get rid of a bunch of junk that I've just sort of accumulated through daily operation, so sort of trim the system down to a minimum working set size. Then I defrag it. Then I make an image of it. And so that's sort of just an afternoon, or maybe a couple hours of when the mood hits me I decide, okay, it's time to do a little maintenance. I get rid of everything I can first, then I defrag it, then I make an image, and then I feel good.

Leo: Good. I'm glad you feel good. I've been for a long time kind of one of those guys who says defragging is voodoo; or, not voodoo, but it's overrated. Do it every few months, that's all you need to do. And...

Steve: It also has the advantage that it's a little bit of a poor man's SpinRite because...

Leo: Right, it does check it, doesn't it, yeah.

Steve: It does make the drive go and move stuff around. And moving stuff around, it makes it read it. And if the drive discovers sectors that are beginning to be problematical, the drive can relocate those to better physical sectors. So it's not just logically moving it, it's actually physically retiring sectors that are bad. You don't get any guarantees that it hasn't missed spots, which is where SpinRite comes in because it does a whole drive read, essentially, and re-verification. But it has a beneficial effect, I think, that is probably greater than its deleterious effect, so long as you're not overheating.

Leo: All right. So keep it cool, man.