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