Multi-Boot Linux, GRUB, Partitions & 1 HD.

[ajinxa]

This post is two fold

The first: Partitioning
I love Fedora but I would like to try out different distro's as well. I am having a difficult time with partitioning my HD. Only 3 primary (or logical) partitions seem to be allowed. I set up a /boot & swap partition only to find that I have a partition left for one OS. Can multiple distros use the same /boot & swap? Can I set up one extended partition with multiple partitions inside of it for multiple OS's? Maybe that's why LVM should be used, this way swap and / can be on one partition.

The second: GRUB
I also have questions with GRUB. If I install another OS it will overwrite the GRUB that was there and will not allow me to boot the first OS it until I add the entry in the new GRUB. How do I know what entries to add if the GRUB gets over written? Then I will need to figure out the old grub entry and change it every time the kernel for that OS gets updated. I have been reading some posts that suggest that Ubuntu likes to be on the MBR. Can I use the GRUB from Ubuntu on the MBR to chainload to other GRUB's? If GRUB is used as a secondary boot loader and is written to the first section of the /boot will other distro's overwrite it when they are installed as secondary bootloaders as well?

Is it possible to do this with one HD? If so how should partitions be set up? What is the easiest way to multi-boot (GRUB) different Linux distros?

I have no idea why I feel the need to have abuncha OS's on my box. I love to be frustrated I guess.

[leadgolem]

In order.
Multiple distros can share a swap, but not a /boot partition. Your /boot is where the kernel is.

You can setup multiple partitions inside a single extended partition for multiple distros.

I would advise creating separate partitions outside of the LVM. Many linux distros cannot read a LVM, so you would need to give each one a separate swap partition. Using a swap partition outside of the LVM would allow you to use that partition as the swap for all of the linux distros you plan on installing.

You can use grub to chain load another grub. You need one grub to be in the mbr, so the bios will load it. The second grub should be on the first section of the /boot partition. Since the second grub will not be in the same location as the first, it will not be overwritten when the distro that installed the first grub gets updated. You will need to add an entry to chain load the second grub to the first. The second grub will be updated by its distro whenever you update the kernel.

It is possible to do this with one hard drive.
Exactly how you set up the partitions is really a matter of personal choice. I would personally prefer not to use an LVM. Ext3 outside of an LVM should be mountable in other linux distros. That way if you mess up one, you can boot to another and fix it. I think using grub to chain load to another grub would be the easiest. I would advise you though, to install the second grub first, and at the end of the drive. Then install the grub for the MBR. I've royally messed up a grub by repartitioning part of the drive after I got my grub setup. This way, you should be able to mount your second grub and correct it from the first. If the grub in your MBR gets messed up, it's much more irritating to fix.

[leadgolem]

If I have made any important omissions, or dispensed bad advice, please post corrections. It has been a while since I ran anything other then fedora.

[lmo]

Here is some info showing what partitioning schemes I am using/planning.
I prefer to use NO LVM, and I prefer to use an extended partition which can contain many partitions (distros, etc.)
Every distro installation can share the same /boot partition and swap. It is fine for all the distros to use the same /boot partition as long as each kernel has a unique name, which is usually the case. They can all use the same "grub" except that Fedoras read/edit a file called "grub.conf" and others read/edit a file called "menu.lst" in the /boot/grub directory.
Once grub is installed and working, it does not need to be "installed" again -- Just the "grub.conf" and/or "menu.lst" file(s) need to be updated/edited.
fdisk -l
Disk /dev/sda: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/sda1 * 1 1305 10482381 c W95 FAT32 (LBA)
/dev/sda2 1306 32636 251666257+ f W95 Ext'd (LBA)
/dev/sda5 1306 1318 104391 83 Linux
/dev/sda6 1319 1383 522081 82 Linux swap / Solaris
/dev/sda7 1384 5962 36780786 83 Linux
/dev/sda8 5963 7531 12602961 83 Linux
/dev/sda9 7532 9098 12586896 83 Linux

df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda9 12G 5.9G 5.4G 52% /
/dev/sda5 99M 17M 77M 18% /boot
tmpfs 758M 0 758M 0% /dev/shm
/dev/sda7 35G 21G 12G 64% /data1
/dev/sda8 12G 7.5G 3.9G 67% /data2


Explanation:
sda1 - Where I install WinX (Prefer fat32 over ntfs -- easy to share with linux)
sda2 - Type f - An extended partition containing logical partitions 5,6,...14
sda5 - Small 100M /boot logical partition relatively low sector (within 10-60GB)
sda6 - Small 512M /swap logical partition (more than 2GB would be too much)
sda7 - Larger /data1 logical partition - Using to hold backups.
sda8 - Mid-size /data2 logical partiton - Stuff to play with, iso's, qemu images
sda9 - Mid-size / logical partiton - root filesystem (9 seemed a lucky number)
sda10-sda14 - Not added yet. Plenty of vacant space in extended partition (sda2)
sda3 - Not added yet. Physical partition. Plenty of vacant space on big drive.
sda4 - Not added yet. Physical partition. Plenty of vacant space on big drive.

I use Extended/Logical partitions (5-14) because there can be many. I may install other distros and future Fedoras on one of these that is vacant. I may also make a big fat32 in one of these for WinX data.

[bob]

Excellent ideas and comments. I'll add that I always use Ext3 instead of LVM since all the distros can use the same swap space (not with LVM). As to the Grub issue, any of the 'buntu's will insist on installing their grub on the mbr, so plan ahead for that. Otherwise, I just add the 'chainloader +1' instructions, as with Windows, to the grub menu.lst and have had no problems.

I'm booting 7 distros at the moment and find that it's more than enough to test and keep things current. Frankly, once you've tried a distro for a few days you'll either love it or tire of it, so I keep 4-5 favorites and recycle the other two partitions constantly. Remember it's not just the installation and setup, but updating the distros that takes time. Did you ever check out that guy who was booting 100 distros? http://www.justlinux.com/forum/showt...hreadid=143973 Insanity!

[ajinxa]

Thanks for all the help. I know have an extended partition with 5 partitions set up and 3 OS's. My GRUB is set up to chainload everything. Thanks for the fast replys as well. Now the fun begins!

[ajinxa]

Thanks for all the help. I know have an extended partition with 5 partitions set up and 3 OS's. My Ubuntu GRUB is set up to chainload everything. Thanks for the fast replys as well. Now the fun begins!

[Dies]

Originally Posted by leadgolem

In order.
Multiple distros can share a swap, but not a /boot partition. Your /boot is where the kernel is.

Since you did ask for corrections...

You can share a /boot partition with as many distros as you want, the only requirement is that the filenames be unique.

If you're only booting Fedora and one other distro this will pose no problems at all since Fedora kernels have very long specific names, but if you plan on booting more than a couple distros from one /boot, it will quickly become a mess and a real pain.

[leadgolem]

Thank you for the clarification. Again, it's been a while since I used anything other then fedora.

[ironeagle62]

Originally Posted by bob

.... booting 100 distros? http://www.justlinux.com/forum/showt...hreadid=143973 Insanity!

Some people really have TOO much spare time!