Computing stuff tied to the physical world

Disk storage

In Hardware on Jun 19, 2012 at 00:01

I recently stumbled across this ad in Byte Magazine of August 1980:

What a bargain! – Now compare it to this one at NewEgg (yeah, no enclosure or power supply, I know):

Screen Shot 2012 06 17 at 02 23 12

(note how this drive has more RAM included as cache even than the total storage on that 1980’s disk!)

Let’s ignore inflation and try to compare storage prices across this 32-year stretch:

  • $4995 for 26 MB is $192 per megabyte
  • $170 for 3 TB is $57 per terabyte – six extra zero’s
  • in other words: storage has become ≈ 3.37 million times cheaper

Then again, hard drives are so passé … it’s all SSD and cloud storage, nowadays.

The amazing bit is not merely the staggering size increase and price reduction, but the fact that this happened within less than a lifetime. Bill’s, Steve’s – anyone over 50 will have witnessed this, basically.

Might be useful to think about this when putting our work in context of… a few years down the road from now.

  1. If anyone has an ST506 interface card, I’ve got a full height 5meg drive in the bottom of (one of my many) bit draws :-)

  2. Go back a further decade and state of the art was ~ another factor ten lower. The Diablo disk was storing 2.5MB on a huge removable platter, shown here stacked on the right so you could build your physical library of data.

    Main memory was severely limited too – the OS was heavily overlaid (reentrant & position independent) to get an acceptable footprint. Furious disk traffic if you set the overlay buffer pool too small. The head servo was precise but coarse open loop – a big step forward in system uptime was for the driver to validate from the preamble that you had actually arrived at the track number requested rather than a neighbour. Once in a while, the random contents of a wrong sector were previously pulled into memory and immediately executed!

  3. The difference is even larger when accounting for inflation. According to Wolfram Alpha it would actually be $13915 in 2012.

  4. As you probably already noticed, there’s that old theorem: “time needed to fill an hard disk is constant”. I verified its validity from my old 40MB on the 386 till the 7.5TB DAS I’m using now (5x2TB WD Green w/ RAID5). I’ll probably see it in practice again when going to an array of 3TB disks, but I’ll try to fool it by expanding the array when needed :) (starting w/ just 3 or 4 disks + parity and reserving at least 4 more ports).

  5. To get a better handle on the magnitude of this lets compare these in equal terms. In todays dollars, after inflation, that works out to $565 per megabyte in 1980 vs. $.000057 (that is .0057 cents) per megabyte today! OR the other way: to get 3 terabytes of storage in 1980 would take $1,695,765,176.53 ($1.7 billion dollars).

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