[Gllug] Large hard drives on old motherboards

[Shevek]

On Mon, 10 Feb 2003, Jonathan Dye wrote:

> Hi,
> 
> I'm looking to get hold of an old pentium computer and stick a large hard
> drive in it to use for storage.  What I'm not usre about is whether I will
> have any problems using a large (say 60Gig) IDE drive with an old
> motherboard.

I doubt you will manage to break the 32Gb barrier since I believe that 
involves an electrical difference in the interface. I suspect you will 
manage to drive anything up to 32Gb in software even though the BIOS can't 
see it. I doubt you will manage to boot off the disk. I never experimented 
much because it was easier to boot off floppy than to even bother trying. 

I've done this:

vendor_id       : GenuineIntel
model name      : Pentium 75 - 200
cpu MHz         : 133.638

Filesystem            Size  Used Avail Use% Mounted on
/dev/hdc1              18G   17G   45M 100% /mnt/mpeg

Disk /dev/hdc: 16 heads, 63 sectors, 39703 cylinders
Units = cylinders of 1008 * 512 bytes

   Device Boot    Start       End    Blocks   Id  System
/dev/hdc1             1     39703  20010280+  83  Linux native

root at desar ~# cat /proc/ide/hda/geometry 
physical     19765/16/63
logical      1240/255/63
root at desar ~# cat /proc/ide/hdc/geometry 
physical     16383/16/63
logical      39703/16/63

The other hard disk in this system is an 8Gb disk. It can't see either in 
the BIOS so I boot off a floppy disk, at which point everything works 
fine.

That machine's been up so many years I don't even know whether it would 
reboot if I tried. I rebooted one the other day and it didn't. That was 
embarassing. It's also why I upgraded to racks :-)

> I know there are problems with the bios being able to boot from large hard
> drives but I understood that as long as the BIOS could see the partition
> with the boot image in it (and the boot image was visible to the BIOS too)
> then it would boot OK and when linux loaded it talked directly to the IDE
> controller.  So I guess my question is that assuming I am right with the
> BIOS issue will I have any problems from the IDE controller and large disks?

I used to do this BIOS hack with my old 386 that would only see 512Mb. I'm 
not sure if this works with more modern drives.

S.

-- 
Shevek
I am the Borg.

sub AUTOLOAD{my$i=$AUTOLOAD;my$x=shift;$i=~s/^.*://;print"$x\n";eval
qq{*$AUTOLOAD=sub{my\$x=shift;return unless \$x%$i;&{$x}(\$x);};};}

foreach my $i (3..65535) { &{'2'}($i); }


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