USB Flash Drive Roundup - 10/2005

The Performance Equation

USB flash drives are really quite simple devices. There are three parts to each USB drive that can actually impact performance: the flash controller, the flash memory itself, and the PCB on which the former two items are mounted. We're not talking about extremely high speed transfer rates here, so layout isn't as difficult or critical as it is with things such as motherboards, but it is a factor in influencing performance, albeit the least visible one.

Pictured here is the PCB of a USB flash drive. The left-most chip is a Samsung NAND flash device, and the other chip is a USBest flash controller. The connector on the right is a standard USB connector.

The problem with USB flash drives, however, is that the controller and the flash memory are rarely constant within the manufacturing of a single drive. In order to keep costs down and maintain a steady supply, most manufacturers obtain their controllers and memory from multiple sources, so buying one drive doesn't necessarily mean that you'll get the same combination of controller and memory that we test here.

Luckily, for the most part, this only applies to the lower end and mid-range flash drives. Even then, manufacturers guarantee some minimum level of performance, generally described somewhere on the packaging itself. But because of this variation in chip suppliers and/or types, performance will vary more than what we're used to between models of the exact same product. The higher end performance-optimized drives don't usually have this problem because the manufacturers put performance on a higher pedestal, thus they will always choose the same high performing chips to be used in these offerings. The manufacturing quantities are also much lower for the high-end, high-performance units, so having multiple sources for the controller and flash memories isn't as important.

Not only do manufacturers use different controllers/flash memories for the exact same product, but they do so at various storage sizes of that product line. For example, a 512MB USB flash drive from Company X may use a completely different controller than a 2GB drive of the same product family. Obviously, the flash memory itself is going to be different across different storage sizes, but do keep in mind that unlike hard drives, greater storage density does not necessarily mean greater performance; in other words, although different sized drives may perform differently, it isn't because of the size of the drive, but rather the actual components used on that particular drive.

There are a number of cases where the 512MB versions of a particular USB flash drive are faster than their 1GB and 2GB brethren, and other cases where the opposite is true. So, while we did our best to compare performance of equal sized drives in this roundup, note that the performance that you'll see here doesn't always map to larger drives. It is worth mentioning that although different sized drives do perform differently, the differences in performance are usually not enough to change dramatically the performance standings that you'll see in our charts.