Using a large disk in an older ThinkPad
Contributed By: Scott Dixon
I've just finished putting a 12GB Travelstar disk into my ThinkPad 560e. Since
I couldn't find much specific information on how to do this, I've written up my
experience. I suspect much of this information would apply to other Thinkpads
as well. Despite a search of the Internet and IBM's ThinkPad support site (and
asking Bill), I wasn't really able to determine for sure whether or not a 12GB
disk could be used in a ThinkPad 560e. But given the small increment in price
between a 6GB and 12GB drive, I decided to buy a 12GB drive and see if I could
make it work. After some experimentation, it became clear to me that the BIOS
in the 560e doesn't support disks larger than 8.4GB since it will not report a
disk capacity of greater than 1024 cylinders. I've flashed up to the latest
BIOS but that didn't correct the problem. This means that anything which
depends on the BIOS for disk I/O (DOS, Windows, and any DOS based utility
diskettes like Partition Magic, etc) will be unable to access disks larger than
8.4GB. This is because the partition table on the disk doesn't match the disk
capacity reported for the drive. Thus, it is impossible to format or boot from
the larger disks.
However, it turns out that Linux works fine with larger disks because it is
smart enough to ask the disk directly what the capacity is and then does it's
own I/O. In fact, as Linux boots up, it puts out a message to that it is
ignoring the incorrect disk capacity information supplied by the BIOS. So Linux
will work fine with larger disks, straight out of the box. The Linux tools for
partitioning and formatting the disk (fdisk, parted) work fine and installation
is completely normal (I did installs of RedHat 6.2 and Mandrake 7.01 without any
problems).
However, if you want to use Windows or have a dual boot installation with Linux
and Windows, you still need to overcome the BIOS problem. The way to do that is
documented on the IBM web site
(http://www.storage.ibm.com/techsup/hddtech/hddtech.htm). IBM supplies two
different programs which can overcome the BIOS limitation. Either one (but not
both) can be used. Download (for free) either one
(http://www.storage.ibm.com/techsup/hddtech/welcome.htm) and making an
installation diskette. I used Disk Manager Disk Go. Just follow the
instructions to install the Disk Go software on your disk and partition and
initialize it. During the installation procedure, a small bit of code called
Dynamic Disk Overlay (DDO) is written at the beginning of your disk (in front of
the partition table). After that, you can install DOS, Windows or Linux
normally. If you are going to install Linux, see the Disk Go instructions in
the Linux FAQ (http://www.storage.ibm.com/techsup/hddtech/linuxfaqs.htm#9).
Also, utilities like Partition Magic will now work fine. The only point to
watch out for is that you must first read the DDO software off the disk before
booting. This happens automatically when booting from the hard disk. However,
if you want to boot from diskette or CDROM you have to follow a special
procedure which is explained during installation of Disk Go. Never access your
disk with Disk Go installed with Windows without using the DDO. Your disk will
probably end up being unreadable if you do. Linux, by the way, knows how to
skip over the DDO and find the real partition table.
I hope this helps you to install large disks on older Thinkpads. Of course, the
same BIOS limitations exists on other older laptops and desktop machines as
well.