large disk and dual boot

Matthias Benkmann matthias at winterdrache.de
Thu Nov 8 06:11:50 PST 2001


On 7 Nov 2001, at 21:52, David wrote:

> Can anyone help me with this?
> I have a laptop with an 8.4GB BIOS limit and I would like to put LFS and
> Windows 95 on a 10GB hard drive.
> 
> Do I need to use a disk manager such as OnTrack?

If you put Linux on the high part of the disk I think you could do without 
a disk manager. Make sure you set LBA mode in the BIOS and set the right 
CHS values. The latter may be a bit tricky. Wrong settings could cause 
mapping differences between Linux and Windows causing data loss. I think 
you need to set the H and S values to those you would use for a 10GB 
mapping (should be documented on the drive itself or in the manual) and 
the C value to the max your BIOS can support (i.e. start out with the 
mapping you would use if your BIOS supported 10GB and then reduce the 
cylinder number). 
To test whether Windows and Linux are really separate, write data to the 
Windows partition under Windows until it is full (with many small files) 
and write your Linux partition until it is full (again use many small 
files). Now delete all these small files and recreate them again and see 
if the other OS' scandisk/fsck complains. If it doesn't, you should be 
okay.

I assume you are building a new system so that you don't have important 
data on the disks. Otherwise make backups first.

Regarding the boot process, you may have a 1024-cylinder problem because 
your BIOS probably doesn't support the calls necessary to boot from beyond 
the 1024 boundary (in that case, *no* boot loader can boot from beyond 
cylinder 1024). I think the easiest solution is to use GRUB and keep /boot 
on the Windows partition (including the GRUB files and your kernels). That 
way you won't have any problems. LILO is not a good choice for this setup 
because it would break after a defrag of your Windows partition that moves 
your kernel.
Of course the root device for the kernel is NOT the Windows partition but 
the Linux partition. Only the kernel image and the boot manager files are 
located on the Windows partition. All the rest is booted from the Linux 
partition as usual. There are no special precautions necessary (such as 
changing fstab, or boot scripts) for the Linux system.

MSB

----
Indecision is the key to flexibility.

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