Ok, my current second harddrive is as follows:

hdb 19Gb
hdb1 / ext3 4.5Gb 24%used says Konqueror.
hdb5 swap swap 666Mb never used says Gkrellm.
hdb6 /usr ext3 14Gb 16%used says Konqueror.

I wish to install Mandrake9.1 on the same harddrive. Can I cut hdb1 and hdb6 in two halves, the first of each pair remaining for Mandrake9.0 and the second ones for 9.1? I can resuse the swap partition right?

How do I have two / and /usr partitions, and how would Mdk9.0 know which were the correct ones to carry on working with?

You should be able to cut them in half, and yes you can use the same swap between distros.

As for how MDK knows which to use, your bootloader tells the system which kernel to use, and which root partition to mount, and the rest of the partitions are specified in /etc/fstab as usual. You can even share the same /boot partition for both if you want....

bulliver, long time no see.

So I dont need to defrag the partitions right? And I wont damage the journels either? I know I cant move the starts of the partitions because of that, but using the end halfs should be fine.

Can I have two partitions named / and /usr? Is that ok because they're really hdb1, hdb6 etc?
What will the new ones default to?

I don't even know if you can defrag, but as long as you chop it a safe distance from how much actual data you have on the partition you should be allright.

This is what i'm saying, it doesn't matter. I'll give you an example from my own machine:
hda1=/boot (shared)
hda2=/ (redhat)
hda3=/home (redhat)
hda4=swap (shared)
hda5=/ (arch linux)
hda6=/home (arch linux)

So: When I boot the grub screen comes up I can choose between kernels (all in /boot ie: hda1) and grub.conf states which partition to mount as root depending on which distro I want to boot. I assume lilo can do the same if you use that.
So if I boot redhat then hda2 gets mounted as root, and if I boot archlinux then hda5 gets mounted, then it just reads fstab to see which other partitions to mount when starting up. (ie: your 2 different /usr partitions....)

You can even share home partitions if you want, so you don't have to copy personal files and settings between two partitions.

If I were you I'd copy the contents from hdb6 to a subdirectory
on hdb1, modify fstab and be done with ;), then install 9.1
on hdb6 rather than trying to split it up further...

What's your lilo(grun?) set-up like?

Cheers,
Tink

Cool, ok, now I just have to work out how to safely cut the partitions.
I think these Lilo options let me change the root partition.

Edit: Hmm, Tinkster, Mr Guru sir, that risks me screwing up my 9.0 install more doesnt it? Not that I've actually changed much from the default setup.

Might it be best to copy any vital files to my primary windows harddrive and then clear the secondary. What would be the ideal setup for 9.0 and 9.1 on 1 harddrive?

Anyone? The best setup for two distros on a 19gig hd? Or is seperating the current partitons recommended?

Well, you have a lot of space on hdb6. I think I agree with Tinkster. 16% of 14GB is around 2 GB, so why not just chop 5GB off, leave that as your /usr partition for MDK 9, then use the remaining 9GB to install MDK 9.1 as you wish...

Is cutting my current / in two too risky? I could easily get another / partition out of it at the current usage.

Dunno, never done it while trying to preserve data. Like you mentioned, you may want to tar.gz everything important up and move it to a partition that won't be touched to be safe.

Well I'm not really that worried as I can always just re-install, nothing much to loose
I dont think anything would have been saved past the 50% mark if it's only at 24% now. Likewise with the /usr partition.

Let us know how it goes....

I assume you just want to give 9.1 a try before upgrading, right?

Well I think I've slightly stuffed my 9.0 install wrt GTK+2 and QT libraries, so I'm more inclined to set up a fresh install rather than upgrade and risk any problems carrying over.
Plus having two installs means I have more to learn and mess with

I take it when I configure Lilo to add my new distro, I specify something other than image=/boot/vmlinuz which links to the 9.0 kernel image? Or cant I have a long or complicated (containing periods) image= arguement?

Yup, you would change the name of your new kernel to whatever you want ie: image=/boot/best_kernel_in_the_world

Run rdev on your new kernel and make sure it points to the right "/" partition.

Ok, I think I'll repartition the drive and check 9.0 works fine still.
Then install 9.1 without installing a bootloader.
Check 9.0 works
Mess with Lilo to enable the dormant 9.1 install.
Check 9.0 again