Partitioning for triple-booting

[radlyeel]

I am planning to rework my big Dell laptop from a boring old Windows XP machine into a triple-boot machine, and am seeking counsel on the partitioning issue. My intent is to install Ubuntu as my main Linux environment, and then to embark on a Linux From Scratch project to see what I can learn there. While my hard disk is being de-fragged, I'm trying to get a solid handle on how the drive should be partitioned. Here's what makes sense right now:

    Windows NTFS  150 GB  XP
    Linux   ext3   20 GB  Ubuntu
    Linux   ext3   20 GB  LFS
    Linux   swap    4 GB  2x system RAM of 3.25 GB
    Shared  FAT32 100 GB

That looked okay until I saw mention of a 4-partition limit. So my questions are: is the 4-partition limit still valid? If so, is it possible to use a single Linux partition and then to somehow subdivide it to have two environments on it?

[rcgreen]

The 4 partition limit is only for primary
partitions. Create an extended partition, and as
many logical partitions as you like.

[radlyeel]

So I could put Windows and Shared on two primaries, and all the Linux stuff on the extended partition, and then boot into any of the three? That would be perfect.

[rcgreen]

Yes, Windows prefers to be on the first primary,
at least that's what people have said about older versions.
Linux can go anywhere.

[rokytnji]

Linux swap 4 GB

is overkill for

RAM of 3.25 GB

Unless you plan to do some heavy compiling. 1 Gig of swap would be enough.

[radlyeel]

Thanks for the feedback. I'd always been told that 2x RAM was a good guideline. And since the same swap space will be used for everything I do on Ubuntu, including some 3D game development, giving up an extra 1% of my disk space seems like a small price to pay.

[Manko10]

I'd always been told that 2x RAM was a good guideline.

It is but only under two circumstances: you have significantly less than 4 GB of RAM and you use a source based distribution or applications which consume a lot of memory. So e.g. for Gentoo 2x RAM would be good in many cases but for Ubuntu you don't need your RAM size twice.
Also when you have enough RAM you don't need so much Swap space. My Computer has 8GB and I run Gentoo. In 90% of the time no Swap is used at all. Only when I do some really heavy compiling some bytes may be in use but the available Swap I have here is still oversized and of course it's no twice my RAM.

[Irithori]

Afaik, swap is used for suspend-to-disk.
On a desktop/laptop you need at least as much swap as you have ram to use that feature.
From that perspective 4GByte swap for 3,25GByte ram sounds about right.

[Manko10]

Not necessarily. You can also use Tux-on-Ice for hibernation/suspend-to-disk which let's you use a swap file instead of a partition to store the RAM contents.

[bonesTdog]

I am working on something similar - triple booting (or more if possible) my old machine. My partitions are set, but my problem has been Grub. It only wants to allow me to boot to two different OSs. Three becomes a problem. I have been using Super Grub Disk to manage my settings but don't really understand what it is doing.

Any advice? I think my Grub file is located on my main (Win XP) partition, but I don't know what I am looking for or what to do when I find it.