Access Time Components

The access time of a disk drive is the time taken by the drive to locate, read, or write data from or to the disk. The access time is composed of two main components:

1. Seek Time
The seek time is the time required by the read/write head to move from its current position to the desired track on the disk. Seek time depends on the distance that the read/write head must travel across the disk.

2. Rotational Delay or Latency
The rotational delay or latency is the time taken by the disk to rotate the desired sector under the read/write head. The rotational delay depends on the speed of the disk and the distance of the sector from the center of the disk.

Access Time Formula

The formula to calculate the access time is:

Access Time = Seek Time + Rotational Delay

Both seek time and rotational delay contribute to the overall access time of a disk. The access time can be reduced by decreasing the seek time or rotational delay, or both. The seek time can be reduced by increasing the speed of the read/write head or by using a disk with a smaller radius. The rotational delay can be reduced by increasing the speed of the disk or by using a disk with a higher number of sectors per track.

Conclusion

In conclusion, both seek time and rotational delay are the main components that compose the access time of a disk drive. The access time can be reduced by decreasing the seek time or rotational delay, or both. The seek time can be reduced by increasing the speed of the read/write head or by using a disk with a smaller radius. The rotational delay can be reduced by increasing the speed of the disk or by using a disk with a higher number of sectors per track.