When Microsoft released Windows Vista, most of the marketing hype focused on the new security features. This wasn't much of a surprise, since Windows XP's security vulnerabilities were nothing short of a PR nightmare for Microsoft. Still, there have been plenty of other improvements made to the operating system that have nothing to do with security. One such enhancement is a feature called ReadyDrive.
ReadyDrive is what Microsoft's marketing department decided to call Windows Vista's support for hybrid hard drives. Don't feel bad if you haven't heard of this feature, as it hasn't received a lot of attention thus far.
What exactly are hybrid hard drives?
Whether or not you have heard of hybrid hard drives, you are no doubt familiar with USB flash drives. USB flash drives use non-volatile flash memory for data storage. Hybrid hard drives use the same storage mechanisms as any other hard drive plus the same non-volatile flash memory found in USB flash drives.
So what's the point of using two different types of storage in a single hard drive? Well, hybrid hard drives are primarily used in laptops. In fact, I can't seem to recall ever seeing a hybrid hard drive that wasn't designed for a laptop -- although they may exist. At any rate, the goal behind using a hybrid hard drive in a laptop is to increase performance and battery life while decreasing the amount of heat produced by the laptop.
This is possible because the non-volatile flash memory acts as a buffer for the drive (typically a really large buffer). As data is read from the hard drive's platters, it is copied to the drive's flash memory. When the data is needed again, it can be read from the flash memory instead of having to be read from the drive's platters. This allows the drive to spin down, which greatly reduces power consumption and wear and tear.
This concept also applies when data needs to be written to the hard disk. Rather than writing the data to the hard drive's platters, the data is written to the drive's volatile flash memory. That way, the drive does not have to "wake up" before the write operation can occur.
Typically, there are only two reasons why a hard drive would have to spin up. One explanation is that the flash memory is full. In such a situation, the drive spins up, and any changes that have been made to the data that is stored in the flash memory are committed to the drive's platters. Some of the data is then purged from the flash memory in order to free up space. Once the operation has completed, the drive spins down.
Reason number two for a hybrid drive to spin up is that in some situations the operating system requests data that exists on the platters but not in flash memory. In those situations, spinning up the drive is the only way to access the requested data.
Are hybrid hard drives right for you?
Now that I have explained what a hybrid hard drive is, and how it works, the big question is whether investing in a hybrid is really worth it. While I don't think that it would be fair for me to answer that question for you, I will say that there are both positive and negative aspects to using a hybrid hard drive.
The most obvious benefit is the power savings. There is little doubt that using a hybrid hard drive increases a laptop's battery life. Another positive is that if you place the laptop into hibernation mode, it will be able to wake up more quickly because the contents of the system's memory have been cached to flash memory rather than written to the hard drive in a typical manner.
Still, the overall performance of a hybrid hard drive is debatable. I have read some reports that claim that hybrids perform better than standard hard drives, but other reports claim the opposite. In my mind, there are two main reasons for this discrepancy.
First, some drives are faster than others. If you compare a fast hybrid drive against a slow standard drive, the hybrid drive will probably outperform the slower one. Of course the opposite is also true.
The other reason why I think this discrepancy exists involves the way data is read and written. If a computer is reading a large sequential file, then most of the data is probably stored contiguously (assuming limited fragmentation). When it comes to reading these types of files, a traditional hard drive is almost always going to be faster than a hybrid drive. However, when it comes to reading small or badly fragmented files, the hybrid drive has an advantage because the flash memory does not have any moving parts. A traditional hard drive has to physically move its heads from one section of the drive to another, which consumes a lot of time. The flash memory portion of a hybrid drive is solid state, though, so reading scattered data is more efficient.
Perhaps the biggest disadvantage to using a hybrid hard drive is its lifespan. Non-volatile flash memory typically has a much shorter life span than traditional hard drive platters when heavily used. If longevity is important to you, then you are probably better off using a traditional hard drive.
|Brien M. Posey, MCSE, has received Microsoft's Most Valuable Professional Award four times for his work with Windows Server, IIS and Exchange Server. He has served as CIO for a nationwide chain of hospitals and healthcare facilities, and was once a network administrator for Fort Knox. You can visit his personal Web site at www.brienposey.com.|
This was first published in July 2008