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Hybrid Hard Drives


Hybrid hard drives have been in the news a lot recently. This primarily has to do with the upcoming release of the Windows Vista operating system. There were even reports that this type of hard drive would be required for system integrators to receive the premium Vista certification from Microsoft. Those requirements seem to have changed somewhat but both Samsung and Seagate have already announced new hybrid drives in development for release this year.

So, what exactly is a hybrid hard drive and what's the big deal? These are exactly the questions that this article intends to answer, but first a little background on hard drives ...

Hard Drive Basics

The primary function of a hard drive is to store non-volatile data for a computer into a magnetic media. The magnetic material is laid down on rigid platters that spin up with a small arm and head to physically move between the tracks on the platters to read or write the data. This is a very efficient way to store a large amount of data thanks to the amount of physical magnetic bits that can be stored on the media, but it has its drawbacks.

The most significant drawback to hard drive storage is speed. It takes time for the drives to spin up to speed and to physically move the drive heads to the necessary locations on the drive. This is one of the primary reasons why it takes a computer system a while to boot up. Much of this time is spent synchronizing the drives to read the data.

A secondary drawback to hard drives is power consumption. It takes a significant amount of power to spin the drive platters. This shortens the battery life for notebooks computers. Sure, the drives can spin down to help save power, but once again this causes a decrease in the performance of the system as the drives have to spin back up when needed.

Flash Drives

Flash memory is something that is becoming extremely commonplace thanks to devices such as digital cameras and digital audio players. Unlike traditional system RAM, flash memory can store the data in the memory even when the chips have no power. The problem is the cost. They are extremely expensive based on the capacity when compare to things such as a standard magnetic hard drive or standard RAM.

A few companies have announced plans to release flash memory based hard drives. They are often referred to a solid state drives as they have no moving parts like a hard drive but come in a similar form factor for easy installation. Most of these drives cost hundreds if not thousands of dollars for very limited storage space. This makes them impractical for use in most notebook computer systems.

The Hybrid Drive

Just like a hybrid car takes aspects of a standard gas engine with electric motors, a hybrid hard drive takes technologies from a standard hard drive and newer flash drives. Essentially, it is a standard hard drive that has flash memory installed on it as well. The earlier product announcements of the Samsung and Seagate notebook drives have 128MB and 256MB respectively.

Standard hard drives have a buffer or cache memory built into the drive to help boost performance. This takes frequently accessed files and stores these blocks into the cache memory to quickly access them there rather than relying upon the movement of the drive heads. The problem is this memory is small (2 to 16MB) and is volatile or erased when the drive is powered down.

A hybrid drive by comparison uses non-volatile flash memory of a much larger size to readily store frequently used files even then the drive is powered off. This is what gives the largest benefit to the hybrid drive. When a system is first booted up or recovers from a suspend mode, the operating system files and programs in memory can be quickly accessed from the flash memory before the drive has spun up. This will greatly reduce the boot times of systems. It also lets the drive spin down more frequently allowing the system to use much less energy and extend a notebooks overall battery life.

Why Aren't These in All Systems?

In order for the real benefits of the hybrid drive to be usable, the operating system of the computer must be able to recognize the drive as having the flash memory so it can move the necessary files into the flash memory prior to powering down. Without this, the drive will just function like that of a standard hard drive and still require the spin up to access the required files. This is why the drives are not coming out until Windows Vista is about to be released to actually take advantage of the features.

The other problem is the cost. While flash memory is much more prevalent then it was several years ago, the cost of adding the flash memory still puts the hybrid hard drives at a significantly higher price than a standard drive. Over time these costs should continue to decrease making the drives more affordable.

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