I am currently trying to install two distros of linux on the same machine (Debian and Gentoo). I know that the standard method of doing that would be to create a separate partion for each one, but I was wondering if it would be possible to put them both on the same partition. What I was thinking was that the root directory of the partition would have two directories, and then each distro would mount a sub directory as the root (/) partition. The problem is, I only know how to mount a partition as /, not a sub directory. Is what I'm thinking possible, or should I just go with two partitions? Thanks!

erm... what you want to achieve is kinda possible... i would look towards running a chroot environment for one of the distro's or something, but in practise it's just a bit of a non-starter in my opinion. really not something to want to do in the first place. i would personally rather look towards a virtual machine if you seriously could not add another partition.

yeah, you could do that. but it sounds rather horrible - setting up your bootloader correctly, you'd need and initrd, then setting up the chroot etc etc

Then actually using it could become rather confusing.

Unless you want to use two systems at once, it would be far easier to create 2 seperate partitions......

It sounds like what you're attempting to do is create two "virtual" partitions within one partition using directories.
Why not just go the extra mile and do it the proper way with two separate partitions?
You're just making things needlessly complicated for yourself.

one other thins to toss in here would be the use of LVM, which means you can install inside a single partition, but still obvsiouly requires that you are already using LVM on the current distro, and both distro's you are using are happy to support it properly.

lvm? how are you figuring that acid?

Why not just use debian? Why would you want to run anything other than debian?

well that's what LVM does... partition contains physical volumes, physical volumes contain logical volumes, logical volumes are therefor used instead of disk partitions

yeah, i love my LVM. I've never thought of booting into a different logical volume, i must say!

OK - thanks for the info everybody, that totally answers my question. I was mainly just looking to see if I could save some space (with two partitions, I may run out of space on one before the other), but it's not really that big of an issue. My reason for installing two at once on the same machine was to compare them directly on the same hardware, but it doesn't sound like I'd get a fair test if I had to boot one from the other anyway. I'll just keep it simple this time, but I may look into LVM later. Thanks!

sadly i don't even think that that's a joke... gotta "love" debian users. they manage to stereotype themselves so noone else even has to think!

Yeah, ive also noticed the phenomena.. d: .. Especially against slackers (;

Sorry about that. That was a joke. I was just trying to having some fun. I was in a weird mood. On the other thread I posted that the bible said that only debian users would be saved at judgement day. I thought that was funny because I didn't think someone could *really* think something like that. Indeed that's a problem. I don't even use debian myself (although I use some derivatives). apt-get is nice but debian is not the only way. I use mandriva with much fun and I discovered pclinuxOS, which is kind of a mix between mandriva and apt-get and I like it, although it is only available in english currently (but that will change this summer). I'm turning that into some kind of Red Hat, installing package after package, dependency after dependency from the red hat repositories and that didn't breack yet. LFS is much much fun. Oh and gentoo, arch and and ... BSD! freeBSD is NOT boring. FreeBSD is fun to learn and sooo stable. I didn't tryed openSolaris, but I HAVE to give it a shot. God let's even give that windows vista a chance. I'll probably won't give the bucks for that, but I want to know how it looks like on friend's computers and get nostalgic. Windows is getting old, but this version will be pretty, for sure. I will install slackware on one of my computers one of these rainy week ends, because I haven't managed to try it yet, but have heard so much good about it. Many friends of mine use it with much fun.
In any way, all apologies for offending anybody with my weird mood and please don't take me seriously in the future when what I say is not technical.