Jul 11, 2012
“I have an older computer with a small hard drive, and I’m unhappy about the computer’s speed. Will installing a bigger hard drive make my computer faster?”
Installing a bigger hard drive may improve the speed of your computer, but perhaps not for the reasons you think. Size, independent of other factors, does not influence the speed of a hard drive. In fact, there are several factors influencing a hard drive’s performance, and installing a faster one may provide one of the most dramatic speed boosts that you can give your computer.
I became fascinated by the topic of hard drive performance when I read this document many years ago. While it’s a bit outdated now, the principles are sound and continue to apply to hard drives today. The only things it doesn’t account for are relatively recent developments such as hybrid hard drives and solid-state drives. In case you don’t have a few spare hours available to read it, I’ll explain the two factors that most greatly influence the performance of a conventional hard drive: areal density and rotational speed.
Areal Density
A hard drive stores data on rotating metal platters using magnets. A typical hard drive spins at a constant speed — 5,400 RPM, for example. So, suppose your computer has a hard drive with 500 GB of data on each platter, and you replace it with a hard drive that has 1 TB of data on each platter. If both hard drives have the same rotational speed, then in any given length of time, twice as much data will pass under the read/write heads of the larger hard drive. This doesn’t necessarily mean that the larger hard drive will be twice as fast due to error correction, computational overhead and other factors — but it will be faster.
Rotational Speed
The rotational speed of a hard drive refers to the speed of the motor that spins the drive’s platters. The two most common rotational speeds are 5,400 and 7,200 RPM, and you may also see hard drives with speeds of 4,500 RPM, 10,000 RPM and 15,000 RPM. Like areal density, increasing the rotational speed of a hard drive increases the amount of data that passes under the read/write heads in a given length of time. If your new hard drive has a higher areal density or higher rotational speed than your current one, it will be faster.
Solid-State Drives
Disassembled hard drive (left) and solid-state drive (right), via Wikipedia.
Conventional hard drives have physical limitations that are becoming increasingly difficult to overcome — increasing areal density or rotational speed leads to issues with error correction, heat and power consumption. The solid-state drive is a relatively new invention that has only recently started to become affordable and resolves these problems by storing information on flash memory chips rather than metal platters. Freed of these physical limitations, solid-state drives achieve incredible data transfer speeds. For example, the 3 TB Seagate Barracuda desktop hard drive — one of the highest-performing hard drives on the market with sustained read speeds of up to 193 MB/second — pales in comparison to the OCZ Vertex 3, which reads data at 520 MB/second. This difference is even more remarkable when you consider the fact that the Vertex 3 can sustain this speed from the beginning of the drive to the end. As the Seagate Barracuda reaches the end of the drive, the read speed slows to 93 MB/second. Installing a solid-state drive can make an aging computer feel brand new; Windows launches in seconds and programs load almost instantly.
However, as is typical with computers, there is a bit of a trade-off. If you buy the OCZ Vertex 3, $360 gets you a drive with just 240 GB of storage space. In a desktop computer, you can use your existing conventional hard drive for storage of files that don’t require high-speed access such as pictures and videos, while installing your operating system and programs on the solid-state drive. In most laptops, however, you’re limited to only one drive, which brings us to a new type of hard drive developed by Seagate as a compromise between the two: the hybrid hard drive.
Hybrid Hard Drives
The Seagate Momentus XT hybrid hard drive
At the present time, the only product of note in the hybrid hard drive field is the Seagate Momentus XT. This $200 laptop hard drive combines 750 GB of conventional hard drive storage space with a flash memory cache of 8 GB. As you use your computer, the Momentus XT copies the most frequently used information to the flash memory cache, allowing it to access the cached data nearly as quickly as a solid-state drive. While a conventional 750 GB laptop hard drive loads Windows in about 30 seconds and launches Adobe Photoshop in about 10 seconds, the Momentus XT loads Windows in about 15 seconds and launches Photoshop in about 4 seconds. In most cases, the 8 GB cache should be sufficient to store your operating system data as well as the programs you use most often. Although it isn’t as fast as a pure solid-state drive, the Momentus XT is a good compromise between price, storage capacity and performance.
Benefits of a Faster Hard Drive
Having a faster hard drive will improve the speed at which your computer can read and write data, which means that any task or application that depends heavily on data transfer speed will be improved by this upgrade, such as starting Windows, launching applications, loading game levels and opening large files. The things that a faster hard drive won’t help are tasks that depend more heavily on the speed of the computer’s processor or graphics card, such as games. If you are unhappy with your computer’s gaming performance, consider upgrading the video card instead.
