Posted by: Dave | February 9, 2010

How Traditional Hard Drives Die

We all know hard drives die, but what does it mean that a hard drive will last 1 million hours? I’ve never known a hard drive to last 115 years! Heck, my podcasting hard drive died after just 4 years of abuse. What the heck is going on here?

Let’s first start by realizing there’s many ways for a hard drive to die. The one many folks have encountered is the “Click of Death.” The Click of Death is when you try to start up your computer and you hear a rythmic click. This click is caused by the hard drive being unable to read it’s programming to control its read heads.

Read heads?

Read heads hover over spinning platters inside your hard drive to read information from your hard drive. Think of a record needle on a record player. For those of you who have no idea what a “record player” is, think of a CD and a laser, except the laser is a needle reading the CD by touching it rather than a laser light reading the CD.

If the hard drive cannot read its programming (ironically, stored on the hard drive), then it has no idea how to properly hover the read head over spinning platters within the hard drive. The result is the drive keeps trying to place heads over the platter, but keeps hitting the platter, readjusts and repeats this process. No data can be read from the hard drive and the machine may not even boot.

A trick to getting one last boot out of your hard drive is to freeze it. Freezing constricts all of the metal parts allowing just enough leeway for the programming, required for the hard drive to work, to be read. This will likely only work once or twice, so be sure to back up all data on the hard drive immediately.

By the way, if your hard drive overheats (for example, if it exceeds 200 degrees Celsius) , its metal components will expand to the point that the drive head crashes – making a similar clicking sound. By the way, if your hard drive exceeds 200 degrees Celsius, please don’t touch it with your bare hands. This should not happen when the hard drive is inside a computer, but can happen if the hard drive is being used externally but is lacking a fan or radiant cooler.

Other times, the platters simply wear out. You may ask, how can a solid piece of metal wear out? Well, let me try to explain this without getting into math.

As we all know, computers store data as 1s and 0s. Well… it’s not quite that simple. Individual “bits” of a hard drive are magnetized and demagnetized to represent 1 and 0. However, it’s not a perfect 0% magnetized or 100% magnetized, especially as that same bit is rewritten over and over again. Over time, magnetized may become 75% or 60% and demagnetized becomes 25% or 40%. Incredible software in the hard drive can estimate 1s and 0s from this. However, there comes a point where a hard drive cannot reliably tell 1 from 0 for a bunch of bits next to each other called a “sector.” Once this happens, your operating system will label such a sector as a “bad sector.”

Think of this as the technological equivalent of a bio-hazard zone. No longer is anything read from it nor written to it, it’s simply off-limits. If this was part of a file you were working on, that part of the file is now gone (or in geek terms, the file is corrupt). Unfortunately, this bad sector could wind up smack dab in the middle of your Operating System, causing it to no longer work.

Such situations though can be resolved using advanced data recovery tools such as SpinRite that, instead of relying on the Operating System to tell it that everything is bad, does the hard work of figuring out which parts are salvageable and salvaging data that the Operating System refuses to access.

As for 1 million hour guarantees? Well, like many things in technology, it’s a guess based on an ideal person’s typical use of a hard drive. Basically, it’s an estimate on how long it would take every bit on the hard drive to become bad, which is longer than when much of the hard drive would be labeled “bad sectors” much less succumb to the click of death.

There we go, a simplified guide to how traditional hard drives die. I didn’t go into solid-state or flash drives but the rewriting of data in the same place is a more prevalent issue with such devices as of writing.


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