Are larger hard disk drives coming? Physically bigger drives are the way to more storage capacity

A computer cannot be smaller than the biggest of its internal components (if you discount the external power supply unit). The smallest one at the moment is the optical drive like a CDROM or a DVD drive. The size of these drives, at least on desktops, has not changed since the first drives were launched 15 years ago and are commonly referred to as 5.25-inch components.

Your computer hard drive in comparison has shrunk in physical size with the 5.25-inch format disappearing ten years ago, superseded by 3.5-inch and smaller form factor drives (2.5in and 1.8in).

Manufacturers shunned the bigger formats mostly because spindle or rotation speeds increased tremendously over the years. Current drives spin at 250 rotations per second, a three-time increase over 1995 speeds. The main reason for this increase has to do with surging transfer rates, both in terms of moving and accessing data.

An increase in the physical dimension of hard drives combined with the increase in areal density (the amount of data stored per unit area) could lead to much higher capacities and could eventually compete heavily with tapes.

A 5.25-inch platter offers approximately 80 per cent more surface area as compared to a 3.5-inch one. Combined with current maximum areal density of 245 Gigabit per square inch (GbSI), that’s an extra 200Gb per platter that a 5.25-inch hard drive can offer over and above a 3.5-inch one, with an increase in diameter of 38mm only.

The world’s largest hard disk manufacturer, Seagate has already managed to cram up to 421 GbSI last September which promises even more storage capacity.

A larger platter combined with an emphasis on capacity, means that rotational speeds can be reduced, which has cascading effects on the power usage, noise and heat dissipation per unit storage. Slower spinning speeds mean higher average mean time before failure, lower total cost of Ownership and running costs.

This would in turn make it easier to add more platters. A six-platter 5.25-inch hard drive using 400GbSI areal density and perpendicular technology would store close to 4TB.

Even when spinning at 4200rpm with a relatively slow read and write speeds (>10ms), this hypothetical device would still outperform tape storage technologies both in access time and capacity. Tape media would still be cheaper but would require substantial initial and recurring investments in terms of readers, auto-loaders and sub-system upgrades.

The biggest threat to this “super” hard drive would be the next generation Linear Tape-Open technology, LTO-4, which has some heavyweights behind it. However, tape itself is a very mature technology with not much prospect ahead of it. LTO-3 came three years after LTO-2 and we can therefore expect the 0.8TB LTO-4 tape to appear some time in 2008.

A hard drive with such a high capacity and a low performance would not be used as a primary drive on desktops due to performance issues and price-discrimination as well in the same way a lorry and a high speed Porsche do not normally appeal to the same audience.

This new breed of hard drive, the storage drive or “data tub”, could be used in tandem with a high performance, low capacity drive. It would be perfect for servers and data-farms where price, capacity, heat dissipation and volume are all important issues. Retooling existing manufacturing process to churn out 5.25-inch platters shouldn’t be too much of an hassle.

Another promising technology that can’t be overlooked is flash memory. Combining this with slower magnetic hard disk technology is a tried and tested way of improving performance. Samsung has a great Flash presentation about the benefits of a hybrid HDD. The flash memory actually acts as the usual buffer to the hard drive but instead of the usual 8MB or 16MB of memory, this is upped to 256MB with plans for 1GB cache memory in 2007.

The cache memory will not only actually improve performance but it will also enhance the drive reliability and power consumption due to less wear and tear as the drive spindle less.

There is a definite gap in the market for low speed, ultra high capacity storage to compete with tape. This is especially true as we are witnessing the rise of disk-to-disk-to-tape. With high capacity 5.25-inch hard drives, D2D2T would lose its Tape Node.