Physical Hard-Disk Data Arrangements and Drive Failures?

Tadau asks: "Knowing not much of the low-level and molecular aspects of a hard drive platter, I'm wondering if it is possible to cause a weight change/imbalance on a hard drive platter by say writing solid 1's to approximately 1/2 of a side of the platter? If there is a weight change, then could that attribute to drive vibrations by an ever-so-slightly unbalanced platter, which may result in an eventual drive failure?"

Re:I worked in the HDA industry

[Rick the Red]

So, you worked in the HDA industry. I guess they fired you for not knowing shit, eh?

Oh, wait, I see the problem: You have monkeys in your pants.

Re:April Fools!

[Quixotic Raindrop]

heh ... no, an electron has mass. Photons have no mass. Nor do Photon torpedoes. They do all their damage by making the enemy assume they've been impatcted (bright lights and all that), and computer systems just assume they've been hit and fail. It's funny to watch the expressions on the faces of the remaining Klingons after they've been "hit" with a Photon torpedo, then just as they're about to get all pissed off, you hit them with an electron torpedo. Then the fun really starts!

Re:I worked in the HDA industry

[nytes]

You're pretty much correct - Hint: there are two kinds of hard drives: those that have failed and those that will fail.

Reminds me of a Dilbert...

[MarkGriz]

PHB: This laptop computer weighs too much. Do we have anything lighter?
Wally: Why don't you just delete files to lower the weight on that one?
PHB (curiously studying laptop): That's a thought.
Wally: Technically, I only asked why not.

Historically you're 100% right

[shoppa]

You are, of course, 100% right historically-speaking. Hard drives and tape drives used to use "NRZ" or "Non-Return-to-Zero" recording, where ones were recorded with a magnetic flux change and a zero without a flux change. The problem was actually much more severe with 7-track 556 BPI tape recordings, where the weight imbalance would cause the tape drive to actually jump up and down on the floor.

Once a year, (traditionally, the first day in April) all disk and tape drives were rebalanced by redistibruting ones and zeroes. The "bit buckets" were also emptied on this hallowed day.

This isn't a problem anymore because all modern recording media use "MFM", "RLL", or "GCR" encoding methods, where ones and zeroes are automatically balanced.

One minor technical nit: "ones" actually weigh less than "zeroes". This led to the conclusion that the more data you put on your punched cards, the less they cost to mail :-)