By the end of last year the annual increase had reached 130 percent. With the current pace of miniaturization, some experts believe the industry could reach the limit as early as 2005. Another problem with magnetic disk is it s access speed. Although the capacity of hard-disk drives is surging by 130 percent annually, access rates are increasing by a comparatively tame 40 percent. Thus, disk access speed has become a major bottleneck in the computing system.
Optical disk is other popular device.
CD-ROM is by far the most popular form of optical disk storage. While they offer high-capacity storage, optical disk drives are not nearly as fast as hard disk drives. Access times average 30 to 50 ms, compared with average access times of 8 to 15 ms for hard drives. Also, the read only feature of CD-ROM may not be suitable for many applications. Therefore, the drive must pass over the disk twice to write to it.