Big (> 137GB) Drive Support

[Darrell Shandrow]

Hi Fritz,

Drive geometry and how it relates to a system's BIOS is still something
which I have a bit of difficulty getting my mind around.  I know that a
motherboard with an obsolete BIOS will not work with modern very large hard
drives, and that various limits in cylinders, heads and sectors values in
BIOS have resulted in size limitations, such as the 8.4 GB limit.

But, I think some of this can be gotten around through the operating system.
For example, I installed a 20 GB hard drive into a 1997 ventage system,
performed auto-detection on the BIOS, then successfully installed RedHat
Linux 7.2 onto that drive.  I thought I'd run into some sort of BIOS/drive
size limit, and have to make multiple partitions, but that turned out to be
unnecessary.  I was able to have a small boot partition at the beginning of
the drive, followed by the large partition (somewhere around 18 or 19 GB)
and a swap partition, with no trouble at all!  Note that this is a
single-boot system; only Linux has been installed.  There's nothing fancy
happening like dual-booting.

>From the research I have done, here's what I think is happening.  The BIOS
is auto-detecting the drive, and coming up with CHS for a smaller drive size
than the 20 GB limit, even after doing some sort of LBA translation.
Unfortunately, since I can't see the BIOS screen (that happens long before
the OS loads, and thus no screen reader is running) I can't tell you the CHS
figures the BIOS is generating.  The system then proceeds to boot from the
hard disk's boot sector at the beginning of the disk.  Since that points to
Linux, the Linux kernel loads.  The Kernel is in the boot partition, which
is also the first partition on the drive, so this fits well within whatever
the BIOS drive size limit would be.  At that point, the Linux kernel takes
over disk access functions, and is smart enough to work around the size
limitations.  Am I in the right ballpark on this?  Additional information
would be great.

Thanks.

----- Original Message -----
From: "Fritz" <fkolberg@qwest.net>
To: "PLUG-Discuss" <plug-discuss@lists.plug.phoenix.az.us>
Sent: Wednesday, November 06, 2002 10:22 AM
Subject: Big (> 137GB) Drive Support


> Hello,
>
>                 Does anyone know the status of the support for the new
>                 big (greater than 137GB) IDE drives that are starting
>                 to appear?  I would imagine there are prerequisites
>                 such as a fairly new mobo, BIOS updates, etc.
>
>                 Do most of these drives (e.g. Western-Digital, Maxtor)
>                 include a controller card in their "boxed retail"
>                 versions (or do they rely on the mobo IDE controller)?
>
>                 Reply to list ... TIA.
>
>                 Fritz
>
>
>
> -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> PLUG-discuss mailing list - PLUG-discuss@lists.plug.phoenix.az.us
> To subscribe, unsubscribe, or to change  you mail settings:
> http://lists.PLUG.phoenix.az.us/mailman/listinfo/plug-discuss