Happy 50th, hard drive. But will you make it to 60?

Threatening HDD, flash memory will soon be available in 64GB capacities -- with larger devices coming

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Flash, also known as a disk on module (DOM), is most commonly found in portable media players and Universal Serial Bus drives. Unlike SDRAM, it does not require power to preserve memory contents, eliminating the need for battery and alternate power sources. While flash memory may not be as fast as high-speed RAM, it has an advantage in that it is available in large capacities at relative lower prices, with improvements in both occurring on an annual basis. Vendors, including Samsung, are deploying flash-based solid-state disks (SSD) with ATA and SATA interfaces in 2.5-in. designs for use in harsh environments and notebook computers to support faster boot and restore times while drawing less power than HDDs.

SSDs are available or soon to be available in capacities up to 64GB, and larger devices are on the drawing board. For example, an IDE/ATA or SATA 32GB NAND based flash drive sells for about $1,800 (or less), and prices are continuing to decline. By comparison, a 3.5-in. SATA 7,200-rpm 750GB HDD sells for about $400 to $500. High-capacity (multigigabyte) SDRAM-based SSD devices are also available from vendors such as Texas Memory Systems Inc.

There is a caveat with NAND flash based technologies in that they are not optimum for continuous reuse and recycling compared with RAM and HDDs. This has led to the development of hybrid disk drives that combine a HDD with large amount of flash and RAM to enable the HDD to spin down and I/Os resolved from RAM and flash until the HDD is needed. For example, the Seagate Momentus PSD (power-saving device) combines a traditional 2.5-in., 5,400-rpm 160GB notebook HDD, 256MB of flash and 8MB of RAM cache. Another example of a hybrid HDD is the Samsung Flashon (Figure 3).

Figure-3: Samsung Hybrid HDD (Flashon)

Figure 3:

Samsung hybrid HDD (flashon)

Source: www.samsung.com

As the industry has seen in the past, combinations of different technologies can be expected to appear in storage systems and servers to help address data storage and I/O performance needs. For example, some vendors may incorporate multiple gigabytes of flash as an embedded SSD on server motherboards to complement existing HDDs. Storage vendors may incorporate larger amounts of SDRAM and flash as tiered cache in front of larger quantities of high-capacity 2.5-in. and 3.5-in. enterprise and desktop drives for tiered storage.

Some general trends include the following:

  • Continued decline in pricing while capacities increase for HDD and SSD technologies

  • Larger capacities, smaller footprints, less power consumption, better performance

  • Better reliability and durability with higher mean time between failures (some disks have 5+ year warranties)

  • Hybrid technologies combing HDD, SDRAM and flash as an integrated device

What happens around 2020 is still not clear, and there is plenty of time for new technologies to evolve -- some perhaps even revolutionary. There could be breakthroughs in material compositions and recoding techniques to further extend HDD usefulness while semiconductor capacities increase and prices continue to decrease. Perhaps the holographic storage that we have heard about for the past 10 years or so may finally be ready and economically viable for production sometime in the next 10 to 20 years. It's fairly safe to say that the death of the HDD after 50 years is still greatly exaggerated, so keep an eye on emerging data storage technologies to support storing larger amounts of data in more locations for longer periods of time.

HDD

RAM/SDRAM

NAN Flash

Benefits

Reliable, proven technology with good economics, capacity, along with diverse packaging options

Low power requirement, higher performance for server boot times and improved online transaction processing and I/O-intensive applications

Improved cost vs. RAM, good performance and no need for battery to preserve data when is power lost

Caveats

More power, sensitive to shock, vibration and less performance compared with SSD

Expensive vs. HDD and flash. Battery needed to preserve data during loss of power

Similar to SDRAM along with limited reuse cycles compared with SDRAM and HDD technologies

Use for

Price-sensitive applications that require large amounts of storage with good performance

I/O and time-sensitive applications including OLTP or where power consumption and durability are concerns

Portable storage and media players, consumer products, tiered cache, appearing in hybrid HDD-based devices

Copyright © 2006 IDG Communications, Inc.

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