For example, they can be used to back up the data stored on your hard disks and, next to a modem, they are the cheapest way of transporting graphics data from point A to point B. Without removable media, digital photographers and designers wouldn't have a way to take large image files back and forth to their service bureaus. Placing financial data on removable media and locking it in a safe-deposit box provides a level of security even the most ardent hackers cannot breach. This use also protects vital data from fire or natural disasters. The performance of fixed or removable drives is measured by seek time or access time. Seek time is the amount of time required for the arm of a direct-access storage device to be positioned over the appropriate track.
Access time is the interval between a call for data and the completion of data delivery.
Some are convinced that the only relevant measurement is sustained transfer rate, which measures the average number of bytes per unit of time passing between disk storage and processor storage. The truth is that a fast drive is usually just as fast no matter how you measure performance. Magnetic media Magnetic-based drives are typically based on the technology IBM developed for the original hard disk that used two 30MB platters. It was the basis for the original and wildly popular SyQuest drives. Winchester is not the only hardware choice for magnetic media.