"How big is the hard drive?" is a common question posed when talking about computer systems. Although important, it is normally not performance critical. How fast data can be accessed on the disk drive(s) plays an important role in deciding the system's performance (along with the memory speed). Factors such as seek time and rotational delay (how many RPMs?) as well as the disk drive interface all contribute to the disk speed.
Internal Disk Drive interfaces
There are many interface types to connect internal hard disk drives, CDs, DVDs etc. The approximate maximum bandwidth is outlined below.
|IDE (Integrated Device Electronics): ATA66||66|
|ATA/100 (Advanced Technology Attachment)||100|
|SATA 150 (Serial ATA)||150|
|Ultra160 SCSI (Small Computer Systems Interface)||160|
|SATA 300 (Serial ATA)||300|
SATA would be the typical recommendation for a new PC for the home user due to the speed it provides at the 'right' price. Future SATA performance is also expected to increase to 600 MB/s in the year 2007.
Note: All this being said, typical hard drives today support a transfer rates of around 60 MB/s
Testing your disk speed
You can check the speed of your hard drive using PassMark's Performance Test Disk Test suite, with a choice to run any or all of sequential read, sequential write or random seek plus read/write test. At the completion of the test, it will give a summary of the read/write rate of your disks. The chart below is taken from the submitted baseline results of some of Performance Test users:
The maximim bandwidth from the above chart is 96.8 MB/s and the minimum bandwidth is 38.0 MB/s.