After 50 years, the useful life of the hard disk drive (HDD) is increasingly being threatened by SDRAM and flash-based semiconductor solid state disk (SSD) storage. For example, Samsung Electronics Company has announced plans to release a 64GB solid state disk drive in a 2.5-in. form factor with an IDE/ATA or Serial ATA interface. And current 32GB flash memory is selling for US$1,800 or less. So the questions are, Is SSD ready to surpass HDD in capacity and price? And, Has the HDD reached the physical limits or can the technology be pushed further?
Over its 50-year life span, the HDD has evolved from a 5MB storage device with 50 24-in. disk platters about the size of a household refrigerator to a 1-in. 8GB device found in Apple iPod and other MP3 players. Physically larger than the 1-in. HDDs found in consumer MP3 players and cell phones, 7,200-rpm, 3.5-in. HDDs have capacities of 750GB priced in the $400-to-$500 range with even larger 1TB HDDs just around the corner.
To remain viable as a storage technology, HDDs must continue to improve on price, reliability, durability, power consumption, footprint, capacity and performance. Perpendicular recording technology that is replacing longitudinal recording on HDD combined with other enhancements should extend the useful life of the HDD for about another 14 to 15 years. Researchers like Mark Kryder, chief technology officer of Seagate Technology, estimate that perpendicular recording combined with other technology enhancements should enable the HDD to evolve out to around 2020.
At some point before then, a major technology shift or revolution will be required unless a significant breakthrough in physics and material composition among others can extend the HDD even further. What this means is that since it takes about five years for a technology to be fully integrated into an ecosystem like the storage industry, to be available around 2020 would need to understand what the replacement technology will be sometime around 2015 or so. While 2015 is less than nine years away, that still leaves plenty of time before you will need to unplug your existing storage systems.
Storage technologies or disk systems traditionally have been replaced on three-to-five-year cycles that should enable users to deploy several more iterations and generations of HDD-based storage before some new technology is defined and developed and products are ready for mission-critical deployment. We should start seeing signs of a new major technology shift in about nine to 10 years. However, between now and then, assume that we will continue to see many smaller (on a relative scale) technology improvements and evolutionary enhancements appear.
Perpendicular recording is currently being deployed by major HDD manufactures across their product lines. Using perpendicular recording, more data can be stored in the same form factor (higher density), enabling reduction in number of platters required while increasing capacity, compared to longitudinal recording. There are more improvements in the works for the disk drive, including, better reliability, less power consumption, smaller footprints, continued drop in price per GB and, of course, increased capacity.
A challenge to building larger-capacity and smaller HDDs is the barrier known as super paramagnetic phenomenon. Super paramagnetism occurs when the magnetic particles on an HDD platter become so small that the magnetic energy holding the particles in place representing a bit can be influenced by thermal energy, resulting in lack of data integrity. The traditional approach for recording bits of data on a HDD using longitudinal recording was heading for the super paramagnetic brick wall limiting future HDD growth without having to increase the physical size of a disk drive.
To delay the effects of the super paramagnetic barrier for several years, perpendicular recording is being adopted by major HDD manufactures. For example, in mid-September 2006, Seagate demonstrated a record ariel density of 421G/bit per square inch that should result in future disk drives of 40GB or more for 1-in. and 275GB for 1.8-in. consumer electronics products.
At 421G/bit per square inch, future 2.5-in. HDD (6.25 square inch per platter surface) about two to three years away for notebooks and new generation of enterprise-class 2.5-in. disks should have capacities pof about 500GB. For 3.5-in. HDD manufacturers like Hitachi estimate that we should be seeing 2TB HDD around 2009 or 2010 with 1TB 3.5-in. HDD just around the corner. Smaller consumer HDD improvements for 1.8-in. HDD should have capacities of around 200GB in a couple of years. To put this into perspective, an Apple iPod or other MP3 player could for example have more storage than a typical currently shipping laptop or desktop computer.
To enable the HDD to get out to the 2020 timeframe, perpendicular recording will need to be combined with other types of technology including smaller form factor drives. For example new technology being worked on in R&D labs include heat-assisted magnetic recording nick named (HAMR) or thermal assisted recording (TAR) or bit pattern media are seen as possible technology to be combined with others to continue the HDD evolution until around 2020.