It is my understanding that there is no upgrade path available from Red Hat 9 to Red Hat Enterprise Linux 3, so I doubt you will find anything of that nature in the CentOS installer either.
It does seem a little odd since RH9 is so compatible with RHEL3. You should be able to find more information at redhat.com.
cody
Message: 1 Date: Sat, 3 Apr 2004 19:47:15 -0800 (PST) From: Bart Schaefer schaefer@zanshin.com To: centos@caosity.org Subject: [Centos] Upgrade install using CentOS-3.1 ISO images
Cutting straight to the chase:
When, if ever, does the installer offer an option to upgrade an existing installation, rather than wanting to reformat the disks?
More details than you may want:
I recently acquired a new PC chassis, with no operating system but with a Serial-ATA disk (which I was not expecting when I ordered it). I set the BIOS for legacy IDE mode and installed RedHat 9, then attempted to upgrade the kernel to add SATA support, without much luck.