Ok, so here is the situation. I have a USB hard drive (2.5" 80GB self powered) that I usually have Linux installed on. I use it as a "fix it" drive for when I need to recover a system, or for other special purposes. I've had Debian/Lenny i386 on it running fine for quite some time. No problems there.
Now I just recently purchased a new computer and I'd like to add Debian/Lenny and64 to it (and keep i386 in place for my legacy systems). I'm not quite sure how to go about this. I tried installing them on completely separate partitions, sharing only swap, but this seems like a waste of space. I'm not sure how compatible the two are, like can I share /home, /boot, /var between them too?
/dev/sda1 = Fat32 12 GB
/dev/sda2 = Linux_swap (shared) 2 GB
/dev/sda5 = /boot (32) 100 MB
/dev/sda6 = / (32) 15 GB
/dev/sda7 = /home (32) 15 GB
/dev/sda8 = /var (32) 2 GB
/dev/sda9 = /boot (64) 100 MB
/dev/sda10 = / (64) 15 GB
/dev/sda11 = /home (64) 15 GB
/dev/sda12 = /var (64) 2 GB
I'm also running into issues with GRUB. After I install i386 (first) it works fine. Then after I install amd64 it gives me various errors (17 & 22). I'll manually edit the lines but even then it won't mount he partitions properly, and also has updating issues. I'm not a novice, but I'm not exactly a GRUB guru either. I know I need to define the kernel, then initrd, and the root partition. but it seem when I load up the system, It keeps moving the USB drive. Example: I edit and boot amd64 to use sda10 as the root partition. The kernel loads, initrd loads, and then it detects the USB drive as sdbx. Nothing mounts and the system hangs. I reboot and switch it to sdb10 as root. The system loads and then hangs when the USB drive is detected as sdcx. Argh!!! Now that amd64 has overwritten the boot sector, I can't seem to load i386 either.
I would like to have both the i386 and amd64 kernels in the same /boot partition and listed in GRUB, and share as many other partitions as I can. I'm just not sure how to go about it and still keep it a clean enough system for apt to work with.
I know a few years ago I had my Slackware box dual boot both the 2.4.x kernel and the 2.6.x kernel so I could test hardware compatibilty before I commited to a switch. Both were 32-bit kernels, not one 32 and one 64, I was using Lilo not Grub, and I can't remember how I went about it.
Has anyone successfully done this? I really need some suggestions. Thanks.