Installing Fedora Outside First 4 GB

[Tom Mitchell]

On Sat, 27 Dec 2003, Holden McGroin wrote:
> 
> A friend told me that it wasn't possible to install Linux outside of the 
> first 4 Gb on the disk. Does anyone know if this is true or not?

This sounds like old knowledge that likely does not matter unless
you have a very strange and OLD box.  See LBA magic numbers below.

As always backup your own work and data.

The good news is:  If you have some OS running on a disk and a
free disk or free disk partition to load Linux into just boot the
"first Linux install CDROM disc" and read the instructions and
install Linux.  There is disk inspection code then a dialog
where you can specify where to load Linux.  Load it in the free
disk partition after setting aside a modest portion of it as a
swap partition.  Leave the existing OS in place.  With a modest
swap partition in place a swap file can be added if more swap is
needed later.

The redhat web pages have screens and examples on this stuff.

By my experience windows install tools are not as clever and
stepping on an existing OS is very easy. i.e. I suspect that
installing win2k in the second partition is painfully.

This is the historic context where the xxGB limit comes from.
Snipped from the grub web pages:
(http://www.gnu.org/software/grub/manual/html_mono/grub.html)

    "Support Logical Block Address mode:
    "In traditional disk calls (called CHS mode), there is a
geometry translation problem, that is, the BIOS cannot access
over 1024 cylinders, so the accessible space is limited to at
least 508 MB and to at most 8GB. GRUB can't universally solve
this problem, as there is no standard interface used in all
machines. However, several newer machines have the new interface,
Logical Block Address (LBA) mode. GRUB automatically detects if
LBA mode is available and uses it if available. In LBA mode, GRUB
can access the entire disk."

Depending on how old the BIOS is there may be some cautions at
bootstrap time but not after. Here are some historic CHS mode
magic numbers from a WD site.

   BIOS Dates   May not support
   prior to     drives larger than

   Aug 1994     528MB
   Feb 1996     2.1GB
   Jan 1998     8.4GB
   Jun 1999     32GB

The key is that only initial boot code must be loaded by BIOS
supported code.

If you happen to have one of these OLD boxes remember that a
second disk today is inexpensive and lets you ignore the issue
because you can place a partition with the /boot file-system in the
very early part that the BIOS can access.

-- 
	T o m  M i t c h e l l
	mitch48 -a*t- yahoo-dot-com