I was trying to recall where I picked up this rule of thumb: the cost of disk space grows at +60% a year; or by a factor of a 100/decade.

I was then wondering if their is a name for this analogous to Moore’s law or Guilder’s law.

Imagine my embarrassment the rate for bytes/$ of disks is identical to Moore’s law – I didn’t know that!

• Guilder’s Law: +3 times every 1 year
• Disk space: +100 times every 10 years
• Moore’s Law: +4 times every 3 years, which is +100 every decade

This paper (pdf) is still a very thought provoking read. It has some very interesting things to say about how disk data is getting colder, an how the throat between the processor and the disk needs to take bigger bites and relatively more slowly.

For example it got me wondering if I really ought to go ahead and setup a proxy server in my basement that caches of everything we visit forever. Why not?