2.5" disks to become new standard in 2009

When I first started selling storage, 14" disk drives were all the rage. Then came 9", 8", 5.
Written by Robin Harris, Contributor

When I first started selling storage, 14" disk drives were all the rage. Then came 9", 8", 5.25" and then 3.5" drives - where we've been stuck for the last 15 years - even though they have gotten thinner.

All this shrinkage is courtesy of drive vendor's incredible engineering work. You don't know it - and engineering-dominated vendors hardly think to talk about it - but disk platter feature sizes are smaller than Intel's latest 45 nm fabs can produce.

And Intel's chips aren't rotating 250 times per second, either.

A Lotus Elan vs a Bentley Type-R Disks are mechanical devices. Making them smaller as magnetic densities increase has many benefits:

  • Smaller components have less mass, so motors and actuators can be smaller. Greater shock resistance, less damping and head settling time too.
  • Greater disk I/O density per cubic inch - get more work done in less space.
  • Power, cooling and packaging are all smaller too. Even though data centers don't much care about green computing, it is a nice added benefit.

Translation: the Lotus corners better than the Bentley and uses a lot fewer resources in the process.

The industry is quietly preparing 3.5" drives will be with us for years to come, but the signs of the coming change are unmistakable:

  • 3 years ago the capacity difference between volume 2.5" and 3.5" drives was 4-5x. 160 GB vs 30-40GB. The delta has come down to 2-3x: 1 TB vs 320 GB - and soon 500 GB.
  • High-performance 2.5" drives, both 10k and 15k, with high-end FC and SAS interfaces are now available.
  • The $/GB delta is also dropping. They don't have to be equal because the lower power, cooling, size and greater durabililty translate into real economic benefits for all but the most price-sensitive users.

The first 2.5" arrays are appearing Atrato, Xiotech and RAID Inc. have all announced 2.5"-based storage arrays that offer some compelling advantages over 3.5" arrays.

  • Atrato puts 160 spindles into a 3 rack unit box
  • RAID Inc puts 12 15k drives into 1 rack unit pizza box
  • Xiotech doubles the number of spindles - with the same power and cooling - over their 3.5" version of their new ISE

The Storage Bits take Smaller disks and smaller arrays are Very Good Things. We get more I/Os for a given power, cooling and volume investment. The drives get more reliable. The $/GB goes up, but volume production soon pushes it back down.

So I'm calling it: by the end of 2009 most new storage arrays will be announcing with 2.5" drives. High-end workstations, like the next-gen Mac Pro, will be both smaller while containing more drive bays.

Low-end consumer desktops will be the last to transition, but even they will by the end of 2011. The last 3.5" disk will roll off the assembly line in 2014.

Remember, you heard it here first.

Comments welcome, of course.

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