On 12/23/2009 07:29 PM, John R Pierce wrote:
Ross Walker wrote:
I think you might be confusing CAV with CLV of optical drives. http://en.m.wikipedia.org/wiki/Constant_Angular_Velocity
no, I'm not. most HD's ('green drives' complicate this some) spin at a constant RPM, so the rotational latency is the same on the inner and outer tracks, an average of 1/2 turn, about 4mS for a 7200 rpm drive, and 2mS for a 15000rpm enterprise drive . However, the data rate changes. so the outer tracks have more data on them, which is read at a higher speed in megabytes/second
That's why in ancient times one was setting up partitions so that the swap area was the the beginning (mostly the outer tracks of the HD -- never hit a drive that did it the other way round) of the drive.
Try it yourself, get a spare HD and create three partitions on it, two smaller ones at beginning/end of the drive, the third one filling the gap between them; install bonnie++ and compare the transfer rates.
Timo