Re: Disk geometry from /sys

From: Bill Davidsen
Date: Thu Apr 10 2008 - 09:55:16 EST


Francis Moreau wrote:
Hi,

I'm trying to know the geometry of my hard disk from a bash script
and that's the reason I'm looking in /sys. The reason is that I'd like
to figure out the size of a cylinder without doing a
ioctl(bdev, HDIO_GETGEO, &geo)

Unfortunately I can't find anything useful and this is certainly a sign
that I'm doing something wrong.

Or maybe can I simply assume from my script that the geometry
is always heads=255 and the number of sectors per track is 63 for all
disks.

Looking at parted(8) source code, I can find this:

/* The GETGEO ioctl is no longer useful (as of linux 2.6.x). We could
* still use it in 2.4.x, but this is contentious. Perhaps we should
* move to EDD. */

Could anybody give me some advices ?

Given that the connection between any modern disk geometry and the assumption of a fixed number of sectors per track is pretty tenuous, I'm not sure any of the sizes, BIOS, boot program, or OS, are more than convention anymore.

--
Bill Davidsen <davidsen@xxxxxxx>
"We have more to fear from the bungling of the incompetent than from
the machinations of the wicked." - from Slashdot
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