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[ The PC Guide | Systems and Components Reference Guide | CD-ROM Drives | CD-ROM Performance and Reliability ]

Seek Time

The seek time of a drive refers to the amount of time that it takes to move the heads to a specific part of the disk in order to do a read. The amount of time that it takes of course depends on how far away from the destination the heads are; in most cases seek time is measured as an average for a typical random read on the surface of the disk. The seek time metric is discussed in full detail in the section on hard disks.

In actual fact seek time as a metric is used for indicating the performance level of hard disks much more often than it is for CD-ROM drives; for CDs it is much more common to see the access time metric stated, of which seek time is a component. For this reason it is often difficult to discern exactly what the seek time of a CD-ROM drive is, however access time is just as useful a metric (if not more useful) in indicating the true performance level of a drive. See the section on access time for more.

Overall, CD-ROM drives have much poorer seek time performance than hard disks do. They use a much less efficient head actuator mechanism that causes them to take much more time to position to different tracks on the surface of the disk. This is probably because of the legacy of CD-ROM technology, which started out with audio CDs. When listening to an audio disk the only time a random seek is done is when changing music tracks, which is done very rarely.

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