Arch Linux

Ranguvar

Member

Registered: 2008-08-12

Posts: 2,549

LVM with multi-boot

Hello,

I often experiment with multiple different operating systems on my computer. For all intents and purposes right now, I have one 500GB hard drive. Obviously, the four primary partition limit gets in the way. I thought about using a GPT partition label instead of the typical MSDOS label, but GPT still has spotty support - notably, OSen that rely on the non-GNU (linux-utils) fdisk for their install fail, which includes Slackware. I don't doubt that there are ways around it, but LVM I've also heard has a workaround to the partition limit. fdisk works fine with LVM (sort of), and most modern recovery CDs and installers can do LVM.

I have looked at a lot of HOWTOs and other info on LVM, but I still don't get some stuff, particularly how my system would be set up if I wanted a multi-boot. Say, Arch, Funtoo, Slackware, CentOS, Plan 9, and Windows XP. Just an example

Well, Windows XP doesn't work natively with LVM, so it'd have to be on its own primary partition. I also need a primary partition outside of the LVM for Grub - or maybe not, since I'll be using Grub 2, which has LVM support, I believe? But beyond that, how would everything be set up? I will probably want one separate home logical volume(?) to use with my main OS (Arch) and to mount easily if I need files from other OSen, a separate /boot for each Unix-like OS... I'm just not sure how this will look, especially if I want said separate /boot to be a different file system than the root. It would need to be on a different LVM partition, correct? And is there a limit to the number of LVM partitions? I'm guessing LVM partitions are logical partitions... so they have the logical partition limit (yes, there is a limit)? Not a huge deal... but does that mean I _do_ need to have a separate primary partition, since the LVM ones are logical?

Oogh.

Any help would be much appreciated

Marcel-

Member

From: Utrecht, NL

Registered: 2006-12-03

Posts: 266

Re: LVM with multi-boot

I've no experience with LVM whatsoever, but I just read some documentation [1] [2]. From this I conclude:

1) Indeed you need Windows on a separate partition.

2) You put the logical LVM-partitions in an extended partition (from the original partition table's point of view).

3) You don't need a separate partition for Grub. But you need a separate partition for /boot when you use LVM. Grub2 can handle logical LVM-volumes, but for safety reasons (and hey, you're not going to resize your /boot that often) I'd put /boot on a separate, primary partition.

4) If those OS's can handle it (Linux flavours), you can put several kernels (of different OS's) in one boot partition, preferably a primary one (I'm also planning to put a Linux-based rescue disc in /boot on my new machine, as it doesn't have an optical drive; and yes, I know that when my hard drive crashes, I can't use this rescue disc, but, in that case, there's not much use to ).

I hope this makes something more clear.

Ranguvar

Member

Registered: 2008-08-12

Posts: 2,549

Re: LVM with multi-boot

Thanks, I think that helps, especially the last link