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Re: grub doesn't worj on my primary drive...

On Tue, Jan 02, 2007 at 03:08:14PM +0000, Michael Fothergill wrote:
> Dear Debian folks,
> Thanks a lot for the advice.  I have been reading the GRUB documentation.  
> I found out that my error is of the following nature:
> 18 : Selected cylinder exceeds maximum supported by BIOS
>    This error is returned when a read is attempted at a linear block 
> address beyond the end of the BIOS translated area. This generally happens 
> if your disk is larger than the BIOS can handle (512MB for (E)IDE disks on 
> older machines or larger than 8GB in general). f the following nature:
> I didn't get this problem when I installed Sarge.  It might have been 
> because I chose the ext2 filessystem not the default for Etch which is Ext3 
> (I think).  I could do a minimal install of Sarge and then upgrade to Etch.
> I am now getting the idea that rescue mode means any old way of getting a 
> basic shell working in your newly installed OS and then going to the 
> directories where grub lives and messing with them until you can get grub 
> working properly.
> Suggestions on a potential cure  to this old BIOS and too new disk problem 
> is welcome.
> Regards,
> Michael Fothergill

This is probably because the files it needs during boot-up are not at 
the start of the hard disk, and so are inaccessible to the BIOS.  Maybe 
they were when you were running sarge, by luck, but in the new etch 
version they happen not to be.

The way to keep this from happening is to have /boot on a separate 
partition at the start of the hard disk.  /boot is supposed to contain 
all the files that might have to be read by the BIOS on initial boot-up.

When you create /boot, make it at least twice as big as you'd expect 
from du /boot -- that way if you someday upgrade a kernel there will be 
room for both the old and new kernels until you're happy with the way 
the new one handles.

As to how to go from the old hard-disk layout to the new, well, you'll 
probably have to repartition.  That will wipe all your data.  Don't do 
it without a very reliable backup, and it may be easiest to backup, 
reinstall, and then restore all user-data.  You do have some idea just 
*where* your user-data are, do you?  Better back up everything in case 
there's some maverick user data in odd places (such as /var/spool/mail).
But only restore the real user data -- you don't want to clobber your 
newly installed system.


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