A Thorough Job of Hard Drive Data Destruction

Scrubbed hard drive platters
Scrubbed hard drive platters

What’s wrong with this picture?

A friend rides herd on a college data center and reports that one of the hot spares in a drive array started complaining about errors. By the time he got to it, things had gone from bad to worse to worst: the drive was spinning, but its data was gone.

He removed all the head frippery before giving me the carcass, but the platters are exacty as they were when he ripped through those “Warranty Void If Removed” stickers.

Even though disk platters are now made of glass in order to achieve adequate flatness tolerances, you’re not supposed to be able to see through the things. There’s a bare millimeter of untouched plating on the inner and outer rims; everything else is finely ground glass.

Evidently the drive suffered a head crash or some part of the plating peeled off, after which the debris acted as grinding compound under the heads on the rest of the platters. Eventually the internal filters clogged and the ensuing dust storm scrubbed the glass platters clean.

He said the inside of the drive was filled with impalpable silvery dust. Another friend deadpanned “Oh, so all the data was still in the drive, right?

We decided that sorting all those dust grains into the right order would tax even Iranian “students”.

More than you likely want to know about hard drive platters resides there.

2 thoughts on “A Thorough Job of Hard Drive Data Destruction

  1. Excellent photo…. and good observation. Technically, the actual spec for particles collected from the media surface to be considered beyond reconstruction is 1/1250th of an inch. This diameter represents a circumference just slightly smaller than would be necessary to accommodate a single 512 byte block from a recent manufacture high capacity hard drive. Where a single sector is considered to be the smallest recoverable block of data.

    In the world of data destruction, when handling information of high classification levels, this data, upon reaching the end of its usable life, must be destroyed to a point of absolute destruction. Where, ‘absolute destruction’ means that the process must assure that the data can not be resurrected by any means possible, using current or future recovery practices. Currently, this would require that if a drive HDA (Head Disk Assembly) or its media were to be shredded, the screening size of the resulting particulate should be no larger than 1/250th of an inch (according to the Center for Magnetic recording Research at the UCSD). This diameter had been stated as 1/125th of an inch at the beginning of 2008.

    The old screening size is an easier spec to attain. However, at 1/250th of an inch, the cost to process a drive to this size is much higher. Better practice would dictate using a logical process such as Secure Erase for logical data sanitization before shredding to the old 1/125th spec to attain the same or better results.

    However, a drive with a pair of clear coating free discs and a fine slurry of silvery dust is pretty impressive.

  2. Yeah, you can almost hear the ECC algorithm:

    “Dave, my mind is going. I can feel it. I can feel it. My mind is going. There is no question about it.”

    And then there’s just no plating left…

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