How to Multi-boot (Maintain more then 2 OS)

[bodhi.zazen]

How to Multi-boot (Maintain more then 2 OS)

Be aware this thread is from 2008 and is out of date as it uses grub 1. I have left it for historical reasons, but it is no longer maintained. Links may be broken. Please see any of the grub 2 guides, either on the Ubuntu wiki or forums.

Ubuntu wiki grub2
Ubuntu forums grub 2
Grub 2 Tweaks

Dual booting is fairly straight forward, but what happens when you would like to boot multiple (more then 2) operating systems ?

If you are new to Ubutnu, or wanting "simply" to install Ubuntu and Dual boot with Windows, this is not the best tutorial, although you may find it informative. Please refer to this wiki page:

https://help.ubuntu.com/community/GraphicalInstall

In this how-to I will cover primarily booting multiple Operating Systems, primarily Linux Distributions (Versions), using GRUB. For other OS, see the following links :

1. Booting multiple versions of windows can be tricky as you need to "hide" the various windows installs from each other.

http://users.bigpond.net.au/hermanzo..._MultiWindows_

2. BSD can bee more cryptic :

http://www.ubergeek.co.uk/howtos/gru...windowsxp.html

3. NetBSD and OpenBSD :

http://www.linuxselfhelp.com/gnu/gru...er/grub_4.html

Note to Vista users: Please refer to this link (EasyBCD) http://neosmart.net/wiki/display/EBCD/Ubuntu


Contents:

1. Prerequisites ~ "things you should already know".
2. General overview of the boot process.
3. Partitioning.
4. Sharing partitions.
5. Install a new OS, manually configure GRUB.
6. Automate maintenance of GRUB with Chain loading.
   
   Example.
7. Automate maintenance of GRUB with "configfile".

To automate maintenance, either chainload or configfile (not both).

Prerequisites ~ "things you should already know" :

You must have a solid understanding of partitioning and partitioning naming (both Linux and GRUB numbering schemes). While Windows letters partitions ( C:\) , Linux uses /dev/sdxy (or /dev/hdxy) and Grub numbers partitions starting with 0.

If you need a refresher on partitioning terminology see this link :

Partitioning basics

For this tutorial, think of each installation as needing both a root ( / ) partition and a boot directory (or separate /boot partition if using XFS, LVM, or encryption).

You will also find it helpful to have some understanding of grub configuration. Hermanzone is was great resource for grub (The grub 1 information is no longer maintained).

http://users.bigpond.net.au/hermanzone/p15.htm

If you understand partitioning and basic GRUB configuration, Mult-booting is not too hard.

Hermanzone grub 2 page is located here



General overview of the boot process :

The details of the boot precess are beyond this tutorial, but here is a nice summary from Wikipedia :

When a computer is turned on, the computer's BIOS finds the primary bootable device (usually the computer's hard disk) and transfers control to the master boot record (MBR), the first 512 bytes of the hard disk.

The MBR contains GRUB stage 1. Given the small size of the MBR, Stage 1 does little more than load the next stage of GRUB (which may reside physically elsewhere on the disk). Stage 1 can either load Stage 2 directly, or it can load stage 1.5: GRUB Stage 1.5 is located in the first 30 kilobytes of hard disk immediately following the MBR. Stage 1.5 loads Stage 2.

When GRUB Stage 2 receives control, it presents an interface to the user in order to select which operating system to boot. This normally takes the form of a graphical menu, although if this is not available or the user wishes further control, GRUB has its own command prompt, where the user can manually specify the boot parameters. GRUB can also be set to automatically load a particular kernel after a timeout period.

Once boot options have been selected, GRUB loads the selected kernel into memory and passes control on to the kernel. At this stage GRUB can pass control of the boot process to another loader using chain loading if required by the operating system.

http://en.wikipedia.org/wiki/GNU_GRUB


/boot

The boot directory is normally on the root ( / ) partition and contains, amongst other things, your kernel(s), initrd (initial ram disk), and grub (particularly menu.lst).

A separate /boot partition is required with GRUB if you use XFS, LVM, and/or encryption for your root partition.

You can not share a /boot partition (the problem is that most distributions will overwrite your /boot partition when you install them).



Partitioning :

In general I allocate 512 Mb for a boot partition (if needed), 5-10 Gb for the root partition ( / ), and a separate /data partition for user data (40 - 100 Gb).




Sharing partitions :

You can not share a /boot partition with multiple distros.

Swap

Your swap partition can be shared between Linux distors and even BSD (you need only one swap). The problem may be that some distros will automatically format your swap space (during the installation), and if it is formatted, the UUID will change. In this event you will need to edit /etc/fstab (on any old OS) and update the uuid or mount swap using /dev/sdxy . If you use /dev/sdxy you not need to update fstab if swap is formatted again during a future install. How to fstab.


Conflicts with a shared /home

While the idea of sharing a /home partition may sound good, use caution in doing so. The potential problems include :

1. A "rude" OS (or the wrong click of a mouse) may format or overwrite /home without asking permission first. Although rare these days, such rude behavior (or mistakes) will result in data loss.
2. Your user is identified to the system by an id number (uid) and not a name. Ubuntu starts numbering users with 1000, but this is not standard. Fedora, for example, starts numbering users with 500. So even if your user name is the same on both Fedora and Ubuntu, you will have different uid. Because the uid are different you will no longer "own home".
3. The other potential conflict is with your configuration or dot ( . ) files in /home. While you may be able to share these files in different versions of Ubuntu, you may have conflicts with other distros or varying versions of applications (gnome, gimp, etc.).

This problem can be "solved" by using different user names with each distro, or better a /data partition.

Shared /data partition.

I advise you make a shared data partition for data you wish to share across distros and leave /home (and the configuration files) on your root partition. You will likely still have permission problems, but this will eliminate conflicts with configuration files in a shared /home partition.

You can minimize permission problems while maintaining security by making a new group, say "data", and giving ownership of the data partition to root.data with permissions of 770.

As with a shared home, be careful not to format or overwrite your /data partition. (or add your data partition to /etc/fstab post-install).




Install a new OS, manually configure GRUB :

Normally, when you install a new OS, you will re-install GRUB to the MBR and GRUB will now point to your new OS when loading Stage 1.5. Many times your new OS will find and automatically add your old OS to the grub menu. If not, you will need to manually edit /boot/grub/menu.lst and add in your old OS.

The "problem" with manually editing menu.list is that you will need to manually update the kernel line of the (GRUB) boot stanzas when you upgrade a kernel on the old OS.

A typical grub stanza looks like this:

title Ubuntu hardy (development branch), kernel 2.6.24-11-generic
root (hd0,1)
kernel /boot/vmlinuz-2.6.24-11-generic root=UUID=b485ef35-1e30-4709-91
initrd /boot/initrd.img-2.6.24-11-generic
quiet

The highlighted kernel and initrd need to be manually updated with each kernel update (Old OS only).

If you prefer to manually edit /boot/grub/menu.lst with each kernel update, you are done.

You can automate the process if you make use of chainloading (see next section).



Automate maintenance of GRUB with Chain loading :


This section is optional, but makes maintenance much easier.

To automate maintenance, either chainload or configfile (not both).

You probably think of chainloader as a method of booting Windows or BSD, but you can boot Linux via chainloading.

As the name implies, GRUB passes the control of the boot sequence to another bootloader, located on the device to which the menu entry points. This can be a Windows operating system, but also any other, including Linux.

http://www.dedoimedo.com/computers/grub.html

The advantage of chainloading includes :

1. The stanzas in menu.lst are greatly simplified
2. Each OS will automagically update menu.lst (in their respective /boot directories/partitions) and you will not need to manually update the boot stanzas when you upgrade a kernel.

The "trick" is you need to install GRUB into your (target) root partition.

By far, the easiest way to do this is to install grub BOTH to the MBR and your root (or /boot) partition with each install.

You can manually install grub (as root) like this :

sudo grub

       [ Minimal BASH-like line editing is supported.   For
         the   first   word,  TAB  lists  possible  command
         completions.  Anywhere else TAB lists the possible
         completions of a device/filename. ]

grub> root (hd0,1)
grub> setup (hd0,1)
grub> quit

Note: You will need to change (hd0,1) to your root partition (or boot partition if you use XFS, LVM, or encryption). ("setup (hd0)" at the grub prompt installs grub to the MBR).

This greatly simplifies your boot stanzas. For each old OS edit the boot stanza to look like this :

title Fedora 8
root (hd0,0)
chainloader +1
boot

Note: Again change (hd0,0) to the appropriate (Fedora) root partition (or boot partition if you used the Fedora defaults and set up a LVM).


Configure GRUB (on your old, chainloaded OS)

Now when you boot, if you select your new OS, if you select the new OS on the grub screen it will boot directly into the new OS.

If you select an old OS, however, you will get a second grub screen. Select the old OS a second time.

If it is working, you can set the grub defaults for the old OS. First boot the old OS and edit the /boot/grub/menu.lst.

You will want to make sure the "default" is 0 and set the "time out" to 0.

## default num
# Set the default entry to the entry number NUM. Numbering starts from 0, and
# the entry number 0 is the default if the command is not used.
#
# You can specify 'saved' instead of a number. In this case, the default entry
# is the entry saved with the command 'savedefault'.
# WARNING: If you are using dmraid do not use 'savedefault' or your
# array will desync and will not let you boot your system.
default 0

## timeout sec
# Set a timeout, in SEC seconds, before automatically booting the default entry
# (normally the first entry defined).
timeout 1

After these changes, when you boot the old OS you will see the second GRUB screen for 1 second (this allows you to select recovery mode if needed).

When you upgrade the old OS to a new kernel the second (chain loaded) GRUB will automatically be updated and no manual edit is needed.




======================


Example:

Imagine dual booting Fedora and Ubuntu with the following partitions:

/dev/sda1 = boot partition (for Fedora)

/dev/sda2 = LVM = Fedora root ( /)

/dev/sda3 = Ubuntu root (this partition contains the boot directory for Ubuntu).

/dev/sda4 = swap

Walk-through:

1. Lets start by installing Fedora first, using LVM and thus /dev/sda1 as the Fedora /boot.
2. Next, from the Fedora live CD, install GRUB into /dev/sda1 (Fedora /boot)
   

   su
   
   root@fedora# grub
   
   
   
   grub > root (hd0,0)
   grub > setup (hd0,0)
   grub > quit

3. Now boot and install Ubuntu to /dev/sda3
4. Again, from the Ubuntu live CD, install grub to /dev/sda3
   Note: This step is not needed at this time, but sets up the Ubuntu OS to be chainloaded if a third OS is installed later.
5. Post install boot Ubuntu. Edit /boot/grub/menu.lst to chainload Fedora
   

   title Fedora 8
   root (hd0,0) <-- Note Fedora /boot partition
   chainloader +1
   boot

6. Boot Fedora and modify /boot/grub/menu.lst, change the time out to 1

=====================

Automate maintenance of GRUB with configfile :

This section is optional and also makes maintenance much easier.

To automate maintenance, either chainload or configfile (not both).

I recently learned of this option and IMO it is by far the easiest method. It is similar to chainloading (which is why I left chainloading first), but takes a single line in /boot/grub/menu.lst.

A sample entry looks like :

title        Ubuntu 8.04
configfile   (hd0,0)/boot/grub/menu.lst

title        Fedora 9
configfile   (hd0,1)/boot/grub/menu.lst

Caveats :

• grub must be installed in the target partition (hd0,1) and (hd0,1) in the above example.
• /boot/grub/menu.lst must exist in the target partition.
• /boot/grub/menu.lst in the target partition must boot the kernel, ie the boot stanza must list vmlinuz and initrd, like this :
  

  title Ubuntu hardy 8.04
  kernel /boot/vmlinuz-2.6.24-11-generic root=UUID=b485ef35-1e30-4709-91
  initrd /boot/initrd.img-2.6.24-11-generic
  quiet

Reference : http://users.bigpond.net.au/hermanzo...#1._Configfile

==================

Next install as many OS as you like, always installing grub into the root ( / ) partition (or /boot partition) of each OS.

Hope this helps making multi-booting a little easier.

Peace be with you,

bodhi.zazen

[Shazaam]

To add a little tidbit you can also use the same procedure with a virtualized multi-boot if you need the space.

[kushykush]

Bodhi: The guidance provided by you is too advanced. Could you or someone on this forum provide guidance as to how a newbie could install multiple operating systems? Here is my scenario:

I have two Sata drives. Vista is on first drive (sda 0,0) which has three partitions.

Ubuntu is on the second Sata drive with its Swap and other partitions.

Ubuntu installed the GRUB correctly (I do not know where). The GRUB menu list displays Ubuntu and Windows/longhorn and gives me the option to boot either.

Now, I want to install SUSE (and then Fedora) alongside Ubuntu on the second Sata drive. What do I do?

I want to leave Vista untouched on the first (0,0) mainly because I do not want anything to happen to it. Ideally, I would like to install Vista, Ubuntu, Suse and Fedora on the first drive. But I do not know how to chain install.

When I go through the SUSE installation CD, it insists on deleting the Vista partition(s). When I direct it to one of the empty partitions along side Vista on the first Sata, it gives me error that it cannot find the root (/) and the boot -- mounts,

When I try to install SUSE on the second Sata (which is currently occupied by Ubuntu), it insists on deleting Ubuntu's partitions.

If I understand the guidance above, what you are saying is that Suse, for example, cannot be installed along side Ubuntu using the usual SUSE install disc? The only way out is installing it manually?

Before I started to install Ubuntu on my second sata (160 gigs) I had created three partitions in the hope that I will install Ubuntu, Suse and Fedora.

I started with my favorite Ubuntu. However, I could not install Ubuntu on the 50 gig partition that I had created because it kept asking me for the root partition and there was nothing in the graphic install program that gave me any guidance as to how that can be done. Finally, I just did a "guided" install. The result was Ubuntu wiped out the other two partitions and now occupies all of my second drive.

Could you please, once again, try to provide guidance in understandable terms or direct me to relevant links?

[bodhi.zazen]

Bodhi: The guidance provided by you is too advanced. Could you or someone on this forum provide guidance as to how a newbie could install multiple operating systems?

LOL Multibooting is moderately complex. If you do not understand what you are doing that is an indication to stop and do some additional reading.

You need to understand basic partitioning, and how both grub and linux refer to partitons.

http://ubuntuforums.org/showthread.php?&t=282018

Next you need to understand how grub works. IMO the easiest is to use chainloader, as outlined above, as that will automate the process greatly.

I advise you re-read my how-to and ask specific questions about what you do not understand. I (or others) can try to explain it better and I can update the how to if needed.

If you like, here is another link using grub and chainloader to boot up to 145 OS:

http://www.justlinux.com/forum/showt...282#post861282

The other option, of course, it to install away and hope it works (usually it does). You will likely need to sort out a number of pieces with this approach including how to manually update grub with kernel updates and adding grub entries for OS that are not automatically configured at installation of a new OS.

Best grub guide : http://users.bigpond.net.au/hermanzone/p15.htm

Here is my scenario:

I have two Sata drives. Vista is on first drive (sda 0,0) which has three partitions.

Ubuntu is on the second Sata drive with its Swap and other partitions.

Ubuntu installed the GRUB correctly (I do not know where). The GRUB menu list displays Ubuntu and Windows/longhorn and gives me the option to boot either.

Grub is installed into your MBR (the start of you first hard drive) and refers you your Ubuntu partition (? on your second hard drive) for stage 1.5 -> stage 2 (stage 2 is the graphical screen where you select which OS to boot). If you select Windows grub uses chainloader to pass the boot process to the Windows boot loader. If you boot Ubuntu grub continues with vmlinux and initrd in /boot on your Ubuntu partition.

Now, I want to install SUSE (and then Fedora) alongside Ubuntu on the second Sata drive. What do I do?

I want to leave Vista untouched on the first (0,0) mainly because I do not want anything to happen to it. Ideally, I would like to install Vista, Ubuntu, Suse and Fedora on the first drive. But I do not know how to chain install.

When I go through the SUSE installation CD, it insists on deleting the Vista partition(s). When I direct it to one of the empty partitions along side Vista on the first Sata, it gives me error that it cannot find the root (/) and the boot -- mounts,

When I try to install SUSE on the second Sata (which is currently occupied by Ubuntu), it insists on deleting Ubuntu's partitions.

If I understand the guidance above, what you are saying is that Suse, for example, cannot be installed along side Ubuntu using the usual SUSE install disc? The only way out is installing it manually?

It should all be doable, it sounds like a problem with either the SUSE installer or possibly your understanding of how to proceed with installing using manual (custom) partitioning (hard to know). It has been a while since I installed SUSE, you will need to understand and use the manual partitioning option (I know SUSE can be installed as you describe as I have done it before). If that fails, I advise you ask for advice on the SUSE forums.

Before I started to install Ubuntu on my second sata (160 gigs) I had created three partitions in the hope that I will install Ubuntu, Suse and Fedora.

I started with my favorite Ubuntu. However, I could not install Ubuntu on the 50 gig partition that I had created because it kept asking me for the root partition and there was nothing in the graphic install program that gave me any guidance as to how that can be done. Finally, I just did a "guided" install. The result was Ubuntu wiped out the other two partitions and now occupies all of my second drive.

Could you please, once again, try to provide guidance in understandable terms or direct me to relevant links?

I assume Ubutnu boots ? If so, it should all work out just fine. If not, then you likely have an issue with your BIOS. Bios is variable, confirm that the second hard drive is recognized by the bios and at least one partition is flagged ab bootable (I do this with fdisk)

http://tldp.org/HOWTO/Partition/fdisk_partitioning.html

So again my best advice is to step back and do a little prep work. Again, if you get stuck feel free to ask questions, the more specific the question the better we can assist you.

As an aside, personally I give each OS 10 Gb for the root partition and use a larger shared data partition.

[eMxyzptlk]

Sharing partitions ::

You can not share a /boot partition with multiple distros.

That's not true dude, you can share /boot partition, you just need to know how to do it, I share one /boot between all the distros I use, in each distro I mount the boot partition to /common-boot and I have /boot a symlink pointing to /common-boot/DISTRO with one shared grub under /common-boot/grub, of course mounting to /boot would work perfectly though you'll end up with many files and you probably won't tell which one belongs to which distro

I have 2 Linux ( Gentoo/Ubuntu ), One Windows, one Mac os X and on external hdds I have Solaris and FreeBSD all working fine

[bodhi.zazen]

That's not true dude, you can share /boot partition, you just need to know how to do it, I share one /boot between all the distros I use, in each distro I mount the boot partition to /common-boot and I have /boot a symlink pointing to /common-boot/DISTRO with one shared grub under /common-boot/grub, of course mounting to /boot would work perfectly though you'll end up with many files and you probably won't tell which one belongs to which distro

I have 2 Linux ( Gentoo/Ubuntu ), One Windows, one Mac os X and on external hdds I have Solaris and FreeBSD all working fine

I am glad you found a system that works for you (and it is a neat work-around), but

/common-boot != /boot

As a general warning (to others), if you create a partition and, during the installation(s), mount it at /boot there is a high chance it will be formatted and overwritten when you mount it as /boot during your second installation. This will leave your first installation un-bootable.

I know it is a matter of syntax, but I would not call your method a shared /boot partition. As I have tried to warn you, mounting a shared partition at /boot will not work so smoothly.

[kushykush]

OK Bodhi here is some more specificity:

1. What program should I use to create partitions. Gparted does not work from inside Ubuntu. Therefore, should I get it on a disc or USB?

2. Assuming I am successful in creating two more partitions on my second drive (where Ubuntu resides), how do I begin the installation? Ubuntu, presumably, already has a boot and swap partition. So what do I do on the new partitions?

3. Installing Suse and Fedora: I have these on DVD. Is there another manual way of installing these OSs? Because if I follow the OS installers, they do not let me create /, boot, or a swap. That is my main dilemma. How do you finally install these OSs on the new partitions?

As said I had three, roughly equal, partitions on my second drive. But when I started to install Ubuntu, it's install program wiped out my partitions. I could not (or did not know) how to create the / and swap on the first partition.

Plus, keep in mind that Vista is already installed on the first drive's first partition and Ubuntu on the second drive. Right now Ubuntu's GRUB is working fine as it lets me boot Vista.

If I understand you correctly, I should somehow install Suse and Fedora (after creating new partitions for them) and later do manual manipulation with GRUB. My only fear there is that nothing will boot so there will be nothing to manipulate. Unlike Ubuntu, both Suse and Fedora messed up my Vista installation and failed to boot from the hard drive.

That is the challenge. Keep Vista and Ubuntu working while venturing to install Suse and Fedora without ending up having no boot. Or worse ending up having my boot loader completely destroyed.

I know Bodhi, you have the solution. However, anyone is welcome to help and lead me through this process. I promise if I make it, I will write a step by step easy to understand procedures for multi operating system machines.

[bodhi.zazen]

Sorry for the delayed response.

I think the main problem you have is that you need to set up your partitions (with gparted or fdisk) before you start the installer.

I advise gparted, it is a common tool and will allow you to resize your Ubuntu partitions.

Gparted Documentation

So ...

1. Boot a live CD (you can not resize ubuntu while running from the hard drive). In general partitions should be managed from a live CD.

2. Unmount all hard drive partitions (including swap).

3. Resize your ubuntu root partition to make additional space.

4. In general, 5-10 Gb is sufficient for your root partitions. So make 3 - 10 Gb partitions, one for Ubuntu (resized), one for SUSE, and one for Fedora.

• You can share swap, so make swap = RAM X 2, max 1 Gb or swap = RAM if you have a laptop and wish to suspend / sleep).

5. The complexity here will be Fedora. By default, fedora will want an additional partition for /boot (Fedora uses LVM). So make a 512 Mb partition for fedora /boot

6. Make a large partition for shared data. You should use ext3 and can share this space with ubuntu, fedora, suse, and windows.

7. After making all these changes you may need to update Ubuntu /boot/grub/menu.lst and /etc/fstab (with your partition changes). Here is a thread that shows the issues :

http://ubuntuforums.org/showthread.php?t=316237

8. Reboot to hard drive, boot Ubuntu, save /boot/grub/menu.lst to your shared data partition for referance (in case you can not boot windows). Install grub to the Ubuntu root partition.

9. Boot SUSE , start the installer, install using manual partitioning, mount the target root partition as / , swap as swap, and the data partition as what you wish (/mdeia/data). Install grub to the suse root partition (after installing suse).

10. Boot Fedora, install as above (don't forget the boot partition as /boot).

11. Boot Fedora, edit /boot/grub/menu.lst

Make sure the Windows stanza is "OK" (same as the Ubuntu stanza for windows).

Then use these stanzas for Ubuntu / suse (make sure you replace "(hdx,y)" with the correct root partition in grub terminology):

title SUSE
root (hdx,y)
chainloader +1
boot

title Ubuntu
root (hdx,y)
chainloader +1
boot

If at any point your swap partition is formatted you may to update /etc/fstab for your previously installed distros. The UUID changes if the partition is formatted and many distros mount with UUID=xxx.yyy.zzz in fstab. Use /dev/sdxy and you will not have this problem.

http://ubuntuforums.org/showthread.php?&t=283131

If at any point you can no longer boot Windows or Ubuntu, it would be a matter of configuring grub and you can refer to the back up copy of /boot/grub/menu.lst you saved earlier. Installing additional OS, as long as you do not format old partitions, will not cause you to "loose" windows or ubuntu.

[Herbert_Vaucanson]

Hallo Bodhi,

thanks for the nice howto. I am planning to reinstall the OSes on my PC soon, and your guide comes handy.

I have already checked some other ones on the net, but no-one is really tackling all the issues. Yours is good and easier to understand than most (after some pain with the partitioning basics), so I would like to ask you a couple of questions.

1) somewhere I read about the possibility of installing GRUB in a partition of his own, OS-agnostic and thusly independent of OS reinstalls: I like to reintall from time to time, and everything that makes it easier is a Godsend to me.
Have you experience/suggestions/opinions on this? I was planning to make a GRUB partition of 100MByte and mount it as /GRUB on my Linuxes (Ubuntu and Gentoo). Whenever I reinstall Windows, the MBR will be brutalized and GRUB will be in need of a reinstall. Can I do it from any Linux release I fancy, independently from the one I choose the previous time? (I plan to follow your advice and chainload my grandma, too)

2) I have a fakeraid setup: southbridge Intel ICH9r, 2 SATA2 drives on mirroring. I know that Linux sotware raid is better but I just want a brute disk mirroring working from Windows, too.
I managed to dual-boot Windows and Gentoo from it, but after the reinstall Ubuntu will be in, too.
Do you recon I will have problems? How is the situation with hardware support on Ubuntu installation disks?

[bodhi.zazen]

To keep this thread on topic I will first comment on a dedicated grub partition. This is very easy to accomplish, but a little terminology may help.

Lets start with a /boot partition. A /boot partition contains grub and your various kernel(s) and initrd , everything you need to boot your linux distro.

If you want to have a dedicated grub partition, make a small partition ( 1 Gb is overkill here), install grub into it, but NOT the kernel or initrd. DO NOT mount the grub partition as a /boot partition (Each distro continues to maintain unique /boot partitions, typically on the root ( / ) partition). The grub partition will have (grub) stage 1.5, stage 2,and a menu.lst. You will need to continue to edit and update the menu.lst (on the grub partition) as you add/remove distros.

Now you can either manually maintain the kernel/initrd in the boot stanzas :

title Ubuntu hardy (development branch), kernel 2.6.24-11-generic
root (hd0,2)
kernel /boot/vmlinuz-2.6.24-11-generic root=UUID=b485ef35-1e30-4709-91
initrd /boot/initrd.img-2.6.24-11-generic
quiet

Or go with chainloader, as outlined above :

title Ubuntu hardy
root (hd0,2)
chainloader +1

So that "anatomy" if you will, is as follows. Assume your grub partition is /dev/sda1 or (hd0,0). Your MBR starts the boot process and then passes off to the grub partition where you get a grub menu and select which distro to boot. To set up your MBR (after grub is installed in your grub partition):

With a live CD :

sudo grub

At the grub prompt :

grub > root (hd0,0)
grub > setup (hd0)

Now as you install distros :

1. First, DO NOT use the grub partition as /boot.
2. Second DO NOT install grub into the MBR (as you install your distros). If you do, you will need to restore grub. This is the biggest potential "problem" is that some distros will install grub into the MBR without asking permission .
   
   Or worse, windows will overwrite your MBR.
3. After you install a distro:
   • Restore grub if needed.
   • Mount your grub partition, edit menu.lst, and add the new distro, either manually adding kernel and initrd info or chaninloading as you prefer.

HTH. Here are a few links for reference :

Making a Dedicated Grub Partition
Multiboot with GRUB Mini-HOWTO

As to fakeraid, I am not sure. I would assume you will need a /boot partition outside of the raid and that setting up Ubuntu would be similar to Gentoo. You may wish to search these forums or start a new thread.