Measuring the Speed of a Hard Disk

There are various ways of measuring the speed of the hard disk. The main ones are the maximum data transfer rate, the spindle rotation speed and the seek time.

Maximum Transfer Rate - This is the highest amount of data that can be transferred per second. Common forms of hard disks come with an ATA format. the speed rating of an ATA100 disk would be 100Mb/s. Likewise a ATA66 disk would be able to transfer a maximum of 66Mb/s. Past the older ATA standard just mentioned comes the newer S-ATA standard (serial- ATA). S-ATA 1.0 transfers at a max rate of 1.5Gb/s S-ATA 2.0 transfers at a max rate of 3Gb/s and S-ATA 3.0 can tranfer data a maximum rate of 6Gb/s

Spindle Rotation Speed - The rotation speed of the disk really is the basis of the other two factors of hard disk speed. The faster the rotation speed, the more data can be written per second and the quicker it is to find the correct data on the platter. A Common speed is 7200RPM (revolutions per minute)

Seek Time - The seek time of a hard disk is the average time it takes for the disk to find the data you need on the platters. A fast spinning, highly accurate and responsive disk will have a shorter seek time and will perform much better, especially when the data is scattered around the disk. Seek time is measured in milliseconds or ms.