2.5.40 etc and IDE HDisk geometry

Allan Duncan (allan.d@bigpond.com)
Fri, 04 Oct 2002 23:47:16 +1000


I've noticed that the system's idea of the IDE disk geometry seems to
have changed from 2.4.xx.
In particular, I've got my 40G HD on a Promise PDC20268 PIC, and find
that the (logical) CHS is different, while the LBA sectors remains constant
(and correct according to the HD label).

2.5.xx does have the right values in that CxHxS = LBA blocks, but fdisk and lilo
get a bit stroppy about the partition boundaries that were created from the CHS
that were generated under 2.4.xx, so I will have to patch them up.

Question is - what is determining that initial value that becomes the "logical"
CHS, and does it matter?

The fdisk and friends man pages are a bit vague on this, cfdisk says "picking
255 heads and 63 sectors/track is always a good idea", but I find 2.4.xx uses
nn/255/63, while 2.4.xx uses mm/16/63, and as I dual boot with win98, consistent
partition table behaviour is important to me.

Advice anyone?

Aside - RedHat has dropped cfdisk from util-linux in their distro versions 7.2 ff.
Given the bad words said about fdisk, what did cfdisk do to be ostracised?
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