grub Error 23 'Selected Disk Does Not Exist' - but it does!

Bill Dearborn wjdearborn at
Sat Apr 3 02:09:59 UTC 2004

Attempts to get by the GRUB and blinking cursor all failed. With all
references but the DOS boot menu commented out we still were halted after
the word GRUB appeared on the monitor.

Within the BIOS there is no listing for the geometry of the Hard Drives.
PlugNPlay appears to have identified my Maxtor 120 and WDC 250 drives, but
there are no listings visible for the Cylinder, Head, Sector counts.

Using linux rescue  & sfdisk -l revealed that my hd0 has a Geometry of
14946, 255, 63 while the missing disk as far as GRUB is concerned has the
figures 30401, 255, 63. Linux appears to be able to discover the disks and
to get the information correct. Is there any place within the Linux files
where anaconda would have written what it found as the drive geometry? I
know anaconda identified both disks since it wrote a file to the
/boot/grub directory which identified (fd0) as /dev/fd0; (hd0) as /dev/hda
and (hd1) as /dev/hdb 

More discoveries: after loading grub via the floppy disk, I issued the
command 'geometry (hd1)' and still received the Error 23, then I did used
the same command on (hd0) and received the following: 1023/255/63 - which is
completely wrong and represents a 240 Meg drive. If I understand this
correctly GRUB is confused.

So as a newbie I am wondering where to turn next ... Do I need to attempt to
find a way to re-install GRUB which appears to NOT understand my machine?
Are there other options? Is the GRUB setup command the way to go?

At the moment I have to use GRUB on a floppy and issue the commands to boot
Windows manually just to be able to use the machine.

Help ....

-----Original Message-----
From: Scott Burns [mailto:scott at] 
Sent: Thursday, April 01, 2004 11:26 PM
To: wjdearborn at; For users of Fedora Core releases
Subject: Re: grub Error 23 'Selected Disk Does Not Exist' - but it does!

Bill Dearborn wrote:

>I need some help or direction as to where to find help...
Is the disk geometry correct in BIOS?  I've seen this happen because linux
makes up it's own mind ignoring BIOS.  IT installs grub, grub believes the
BIOS, and Bang!  All dead...

If you boot up the rescue DVD you can check what Linux thinks  the disk
geometry is.

Scott Burns
Mirrabooka Systems

Tel +61 7 3857 7899
Fax +61 7 3857 1368 

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