What is a Hybrid Hard Drive?

R. Kayne

A hybrid hard drive combines traditional hard drive storage on magnetic platters with a compliment of flash memory for fast caching. This allows frequently accessed data to remain instantly available, even faster than resorting to random access memory (RAM). Flash memory is made from non-volatile memory chips, which means it stores data bits without the need of a power source. This is in contrast to RAM chips that lose all data when power is cut.

Traditional hard drives use magnetic discs for storage.
Traditional hard drives use magnetic discs for storage.

A hybrid hard drive incorporates a kind of “personal cache system” or buffer, but instead of on-board RAM, it uses on-board flash memory. Operating system (OS) boot processes stored on flash memory within the hybrid hard drive means boot-up time can be significantly reduced. Also, depending on the size of the flash chip, frequently used programs and files can be instantly accessible without the drive needing to spin up. Hence, the hybrid hard drive spends most of its time idle, even while continuing to read and write to built-in flash memory.

Solid-state hard drives, which have no moving parts, start and operate more quickly than traditional computer hard drives.
Solid-state hard drives, which have no moving parts, start and operate more quickly than traditional computer hard drives.

Laptops should benefit greatly from hybrid hard drives as compared to traditional storage devices that account for a significant portion of battery drain. Samsung Electronics' introductory hybrid hard drive reportedly spins up a modest 30-45 seconds every 30 minutes, saving valuable power. Samsung claims increased battery life between eight and twenty percent, adding a potential 36 minutes to the life of an average laptop battery.

Samsung teamed with Microsoft to unveil prototype hybrid drives in August 2005 and May 2006, and plans to deliver hybrid-enabled laptops to market by the close of 2006. One prototype hybrid hard drive featured a 1-gigabyte flash memory chip, while others featured 128- and 256-megabyte chips. The flash memory is purportedly a cross between NAND (Not And) and NOR (Not Or) architectures, taking advantages from each. However, other manufacturers have their own proprietary solutions for flash memory in the hybrid hard drive.

Hard drives that are flash memory only are referred to as NAND hard drives. The NAND hard drive, or a future iteration, will likely replace the hybrid hard drive in the long run. NAND hard drives have the advantage of no moving parts and all the benefits of flash memory. They also use very little power, are lightweight, produce little heat, and take up nominal real estate. The only factor keeping NAND hard drives from superseding the hybrid hard drive market is that the former will be too expensive to compete until 2009, or so industry experts predict.

In the meantime, manufacturers will be entering the hybrid hard drive market. The drives by Samsung and Microsoft are reportedly designed to work with Microsoft’s newest operating system, tentatively referred to as “Longhorn.”

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