Hack 58 Choose the Fastest Hard Drive

Did you know that the "high performance Brand X" hard drive inside your PC is probably not the highest performance version of the drive that "Brand X" makes? PC manufacturers use the most current disk drive series available from their drive vendor, but typically only the most economical model of that series. Your PC maker buys a select version of the popular disk drive brands, so their "select" or so-called "OEM" components are not necessarily top of the line, even if you think your PC maker is the best in the world.

OEM, or Original Equipment Manufacturer, has become a generic term for products branded or labeled by a "big name" company like Hewlett-Packard or Dell that are actually made by another company. For example, that beautiful charcoal gray or black monitor with the Dell logo on the front is not actually manufactured by Dell but by Sony, NEC, Nokia, or a no-name assembler of PC parts with a license and a big order to produce a lot of Dell-branded products. The big PC makers do not make disk drives; they make a special deal to get a lot of drives from either of three or four different drive makers and then put their name on them. The PC maker makes more profit if they can "OEM" a cheaper but adequately performing disk drive. If you are a do-it-yourself PC builder, you'll also hear the term "OEM" in reference to some of the components that you can buy directly from an online retailer like Newegg (http://www.newegg.com). OEM parts typically come with nothing more than some packaging and a minimal warranty. Compare this to retail boxed versions that include fancy packaging, a longer warranty, and some extras. For example, a retail CPU will usually include a heat-sink/fan unit, while an OEM CPU includes nothing except the anti-static packaging.

Often the same basic drive mechanics and electronics are used across different models of disk drives to minimize manufacturing complexities. Then drives are tested to see if they meet maximum, intermediate, or minimal performance specifications, reprogrammed, and then labeled and sold accordingly. This is similar to the practice of CPU and memory makers that sell the same components at different performance and price points to maximize profits from their manufacturing processes (providing many opportunities to overclock and hack more performance from lesser-rated parts).

Disk drive models from the same manufacturer, in the same model series, differ either by programmed-in or actual speed and access-time limitations, amount of on-drive data buffering, and even total available drive capacity. Western Digital (http://www.wdc.com) openly lists "High-Performance EIDE," "Mainstream EIDE," and "Value EIDE" drive families with essentially the same capacities but different performance specifications. When you go to buy a disk drive, be sure to check specific model numbers and the labeling on the packaging to be sure you are getting the performance you expect. Unfortunately there are no known ways to hack into disk drives, change their firmware or operating parameters, and gain similar performance improvements as you have seen with hacking CPU and memory speeds.

A top-of-the-line model might be available with the following specifications:

• Rotation speed (how fast the disk platter spins): 7,200 RPM

• Buffer size (the amount of on-disk cache memory): 8 MB

• Average latency (the average length of time it takes the drive electronics and mechanics to begin responding to a command to perform a function—seek, read, or write): 4.20 milliseconds

• Average read-seek time (the average time it takes the read/write heads to find a specific disk track and be able to read data from it): 8.9 milliseconds

• Average write-seek time (the average time it takes the read/write heads to find a specific disk track and be able to write to it): 10.9 milliseconds

• Track-to-track seek time (the length of time it takes the read/write heads to travel from one data track on the disk platter to an adjacent track): 2.0 milliseconds

• Full-stroke seek (the length of time it takes the read/write heads to travel from inside to outside of the disk surface): 21 milliseconds

• Buffer-to-disk transfer rate (how fast the data gets written to disk from the on-disk cache): 737 megabits per second

The same drive maker's value-line specifications read:

• Rotation speed: 5,400 RPM (25% slower)

• Buffer size: 2 MB (75% smaller)

• Average latency: 5.00 milliseconds (20% slower)

• Average read-seek time: 8.9 milliseconds

• Average write-seek time: 10.9 milliseconds

• Track-to-track seek time: 2.0 milliseconds

• Full-stroke seek: 21 milliseconds

• Buffer-to-disk transfer rate: 506 megabits per second (30% slower)

Even though the seek times are the same, and both drives support UDMA Mode 5 or ATA-100 I/O performance to the system interface, you can see from the rotation speed, buffer size, latency, and buffer-to-disk parameters that the value-line disk will be slower than the high-performance model.

Why would you want a slower drive in your system? Slower drives are a bit quieter. It's cheaper to make slower drives and reduce the amount of buffer memory; the lower cost of the drive means your total system can be more affordable—but wouldn't you like it to be faster ?

The performance of the disk drive makes a significant difference. The disk drive is the slowest critical component in your system. No matter how fast your CPU and RAM are, the system's biggest bottleneck is the disk drive. A faster drive can make a system with a slow CPU speed bootup and work faster than one with a higher CPU speed (even with the same amount of RAM). Look to the specs and buy the best, especially when shopping for a value-priced PC.

If it's time to upgrade the disk drive in your second PC, consider buying the best drive you can for your main PC and move its drive to the second PC or an external enclosure—no sense giving your old PC something better than your new one has!