Forum OpenACS Q&A: Off Topic: head/sector/cylinder on hard-drives

I want to run IDE Raid 1 on my new OpenACS server, so I went out and
bought a computer with three IBM Deskstar 75GXP 75GB drives (one for
backups) and a Microstar K7T266 Pro motherboard. The mobo has two
extra IDE channels with Promise "Lite" IDE Raid. After fooling around
for a while I decided that I'd use Linux software Raid instead...

Now, when I install RedHat 7.1 and use "Disk Druid" to partition the
disks I find that the head/sector/cylinder settings have been altered
by the Promise Raid. The original configuration was; 16/63/148945 but
is now; 255/63/9345. The size of the disks haven't changed much
though. When I try to change back to the original values using Fdisk I
find that the largest value for cylinders is 131071 or something. So I
must increase the number of heads to keep the full size of the drive.

The question is: What impact does different settings of
head/sector/cylinder have on performance and so on?

Maybe you know where I can read about it?


None, in practise.  CHS settings are basically a fiction of the PC architecture, and drives can (and do) return made up numbers to the BIOS - and different BIOSes may return different numbers (which is probably why you're seeing them change across different IDE controllers).
One EIDE FAQ is at and the more technical stuff from Hale Landis is at, with his document about CHS stuff specifically being at