Why aren't small drives cheaper?

Smaller Is Better, So Why Isn't It Cheaper?I've been wondering when the 2.

Smaller Is Better, So Why Isn't It Cheaper? I've been wondering when the 2.5" form factor will replace the 3.5" drive. After all, the 100,000,000x increase in areal density has seen the extinction of 24", 14", 9", 8" and 5.25" form factors. Areal density keeps increasing, so why haven't we yet migrated to 2.5" small form factor (SFF) drives?

Related to that I wonder why SFF drives are so much more expensive than 3.5" drives. Check it out yourself: a 160 GB 3.5" costs about 2/3 that of a 160 GB 2.5". Here are some answers.

Why SFF drives should be cheaper than 3.5"s

  • Lower material costs. SFF drives weigh a fraction of larger drives. Doesn't metal cost something?
  • Smaller, slower motors and slower, cheaper electronics. Bit rates off the head are significantly lower at 5400 RPM, so the signal processing chips should be cheaper.
  • Shipping and distribution costs lower. A lot more SFF drives fit in a 40 ft. container, the shipping cost per drive should be noticeably lower

Not everything is cheaper just because it is smaller.

  • Read/write heads are the same, per platter, but you need more for a given capacity. R/W heads are a major cost in disk drives, which is why moving from 4 platters to 3, or from 3 to 2 is a big deal for vendors and prices. SFF disks are smaller, so at a given capacity SFF drives require more heads. Today, an 80 GB SFF drive costs the same as a 160 GB 3.5".
  • Learning curves. As production volume rises, costs drop. 3.5" drive volume is much higher than SFF. The move to notebooks is helping, but 3.5" drives go into lots of other applications, such as arrays, that SFF drives haven't penetrated.
  • SFF margins are higher. I want drive vendors to be profitable and they are making good money from SFF drives.

Anything else? I sure hope the vendors aren't getting together in some back room somewhere and divvying up the market. That would be wrong, illegal and very, very stupid.

I would appreciate it if a reader from the industry would give us their take on this in a comment or write me directly. Use an alias and bare all - I'll never tell who sent me the email. Contact info at StorageMojo.

The Storage Bits take In The Innovator's Dilemma, a must-read book for every storage aficionado, Christensen makes the case that form factor changes have been the prime mover behind the rise and demise of most disk drive companies. Now that we are down to so few vendors I doubt that will happen again. Most vendors make all sizes, unless, like Toshiba, the specialize in small form factors.

Consumers are driving disk costs today. As long as we keep choosing capacity over power and size SFF drives won't take off beyond notebooks. But every other form factor transition had the same problem. It will be interesting to see how this plays out.

Comments welcome, as always./