Wednesday, November 21, 2007

The Hard Drive Question


Every now and then, the same question always pops up: is it better to leave my computer on all the time, or will my computer last longer if I keep the computer on constantly?


Well, we're going to answer this one for once and for all. Let's get started!

Let me clarify one thing: the most probable components to "die" in your computer are the power supply and the hard drive. Providing you have surge protection and don't do anything odd with your computer (like rub your feet on the carpet and shock it every chance you get) your power supply should survive the life of your computer without issue. So let's focus this question on the hard drive.

The first thing we need to do is figure out how long a hard drive (HD) is expected to be useful before failing (called the "mean time before failures" or MTBF ). If we hunt around at popular HD manufacturers, like Western Digital, Seagate and Fujitsu, we find that most modern drives have about 1 Million Hours MTBF; they're actually expected to last over 1 million hours of constant use!

Putting that into perspective, that's about 136 YEARS of constant use that the hard drive of your computer should survive. Not bad, eh? Mind you, older drives had less of a life expectancy, like around 1/3 that -- 300,000 hours. That's only about 35 years or so, but still pretty impressive.

Now, let's do a little frivolous calculating. Let's say you lose a day of life from your hard drive every time you shut it down and turn it back on (not that I'm saying that's what happens, but let's just play Devil's Advocate here). An average workday is about 8 hours, so we'll call that a "day" for purposes of this calculation. For every 8 hours of operation, you'd lose 16 hours of operation due to wear and tear on the physical mechanisms that operate the drive. Alright, so then you're going to lose some of the useful life of your hard drive, aren't you? Nope! Even with this over-exaggerated figure, you'd actually extend the life of your hard drive beyond 200 years, just by shutting it down at the end of the day! Even an old HD would benefit, extending it's usefulness up to 51 years. Now on to the real world...

In the real world, your hard drive is most likely to experience failure under normal operating conditions within about the first 3 to 5 years. If it doesn't fail under normal use in that time, you can pretty much expect the hard drive to outlive its usefulness. This would be why most manufacturers have 3 year warranties on their hard drives (although some offer up to 5 years). They know your drive is going to survive if you get past this age, and most of them do.

What can shorten the life of your hard drive? Dropping it is pretty high on the list, but the amount of shock required to damage a hard drive these days is getting fairly high for normal abuses. Usually hard drives need to run within certain temperature ranges, too. Keeping your computer within a range of 0°C and 60°C seems to be about the right temperature range to keep all the components in your system pretty happy. Airflow in and around your computer is the key here. Unexpected power outages can cause damage to your hard drive in some instances. If consistent power is an issue in your area, or if the computer you use is almost always on, you may want to consider purchasing a personal uninterruptible power supply (UPS). Sometimes little fingers finding the power button on an older computer can be an issue, as well; with newer computers this isn't as much of a problem thanks to the power button sending a signal to the operating system (OS) to shutdown instead of just cutting the power.

Regardless of your preference (on or off) remember one thing: always back up your important data, because no matter how reliable a drive may be, there's always the chance of failure. And it will most likely occur just when you need something important!

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