Dual-Booting Ubuntu

Ah, dual-boot. I thought I'd never have to do it again but here I am. But what could possibly be the reason? Have I -- gasp! -- decided to share my hard drive with Windows? Well, not really. I'm actually dual-booting between Ubuntu and Ubuntu.

The reason for this curious arrangement is because of the differences between 64-bit and 32-bit. Oh, for sure, 64-bit is generally better, but there are some functions not available there. Hence, dual-boot.

This is the way I've configured my hard disk:

Device Boot Start End Blocks Id System
/dev/sda1 * 1 608 4883728+ 83 Linux
/dev/sda2 609 19457 151404592+ 5 Extended
/dev/sda5 609 1216 4883728+ 83 Linux
/dev/sda6 1217 1459 1951866 82 Linux swap / Solaris
/dev/sda7 1460 19457 144568903+ 83 Linux

That's 5GB for the primary partition, which is running 32-bit Hardy Heron Desktop. The first logical partition, another 5GB, runs its 64-bit kin. Between them, they share the remaining space for swap and for the /home directory. This means that whatever data I save is available in both instances.

A couple of notes:

I use different user names to log in for the 32-bit and 64-bit partitions, but these user names share the same UID (the default 1000). This means that they have two different user directories but under either instance, I can read and modify data without running into access restrictions. I discovered this "feature" accidentally: prior to my current setup, I also had dual-boot and used the same login names. Unfortunately, I messed up the user configuration while in one partition and ended up affecting the other. My current setup is a little less inconvenient but at least gives me some degree of isolation between the two.

In installing the second Ubuntu partition, I used the Alternate Install disk, the reason being I didn't want it to override the GRUB configuration of the first. Under a normal installation, Ubuntu will always write in a new GRUB: if you're installing Ubuntu AFTER another operating system, you'll end up using the second configuration. As I didn't want this, I used the Alternate Install to load the second Ubuntu and skipped the GRUB portion. Then I simply edited the /boot/grub/menu.lst to add the second partition.

The problem with mucking around your menu.lst, of course, is that once you upgrade kernels (in either partition), you have to reflect the new vmlinuz and initrd settings in menu.lst. But it's a small inconvenience.

Finally, with this dual-boot arrangement, I'm able to create a recoverable image of the second partition using partimage (but more on that next time). The first partition, the 32-bit Hardy, I intend to keep as pristine as possible; the second partition is for all the experiments. If I mess up, it's okay; I can just recover the partition without having to go through a full reinstall. As an added bonus, the backup image is compressed and doesn't take up the entire 5GB.