How to triple boot your PC

24th Sep 2007 | 23:00

How to triple boot your PC

Get Vista, Linux and OS X running on the same PC

Booting more than one operating system can be a problem. Reason being that Microsoft Windows doesn't normally take into account that users might want to run something else alongside it.

As the underdog, Linux has never had this problem. It has always been designed to boot alongside Windows OSes and without this basic functionality, the world would have far fewer Linux users.

This is thanks to the Linux boot loader - the small menu that you normally see after the BIOS screen (POST) and before the Linux operating system starts to launch. It's the boot loader that configures your system to boot and adapt to any installed operating system.

Grub boot loader

Recently, Lilo, a boot loader that could only be modified within the Linux system, has been replaced with another boot loader called 'Grub', which is considered a more flexible solution.

This is not least because you can change the boot configuration from the boot menu itself rather than booting into any operating system, which is vital if you run into problems finding the operating system you need. And problems with multi-boot systems are relatively common - at least in the early stages.

There's no standard for where the boot loader should store its data. The boot loader will normally occupy a space on your drive called the 'Master Boot Record' (MBR) but this is just as volatile as any other part of your hard drive. As a result, you may find that occasionally your MBR will be overwritten during system maintenance or an OS upgrade.

In these cases, the boot menu provided by either Grub or Lilo will disappear and you will instead boot into the default operating system without any other options. To repair your installation in these cases, have a Live Linux CD such as Ubuntu handy to reinstall the boot loader. Your alternative OSes will appear unscathed.

And fortunately, things have improved considerably since the early years of Linux, and if you're installing a simple dual or triple boot system, you're unlikely to have any problems and configuration should be automatic.

Divide and conquer

You need to install more than one operating system before you can dual or even triple boot. Things are much easier if you're starting from scratch with a blank hard drive. This is really the only method we can recommend as you don't need to juggle any valuable data that may already be in use on your drive.

This avoids the most common problem with multi OS installations - resizing partially used partitions to make way for new ones. The problem is that by default, an installed operating system will use all the space on the drive available to it.

When you're starting from a blank drive, you manually create partitions for each operating system using a pre-defined space on the disk. This will avoid any resizing issues. But if you do have data on your system, you will need to ensure it survives a repartition of your drive using a partition resize and management tool.

Windows XP doesn't include one, although Vista does, and you'll need to use either a commercial application like Norton's Partition Magic or try Linux and GpartEd.

You must back up your data first, there's a good chance you might lose everything in the resizing process. After coming up with a partition/disk strategy, the next consideration is the order you install each operating system. This is a relatively easy decision, as the order is dependent on how adaptable each operating system is to anything previously installed on the drive.

Install Windows XP first, as it doesn't take any alternatives into account. XP also expects to be installed onto the first available partition on your drive, and you'll need to use the manual partition selection at installation to make sure this happens.

If you've already partitioned your drive, then just select the first one. If not, create a single partition for XP and leave the rest of the drive empty; you can create the other partitions as you install the other operating systems.

After XP has installed, the next operating system to install is Vista. Perhaps in anticipation of some of the compatibility problems some users experience with Vista, the installation routine for Microsoft's latest operating system will automatically recognise an XP installation, and configure the Windows Boot Manager to add a menu at boot time to select between the two.

You will still need to use the manual option for installation in the Vista installation process to stop the entire drive being used, and as with XP, create a new partition after your XP partition. Choose Custom (Advanced) | Drive Options.

Click on the 'New' button on the 'Where do you want to install Windows?' window unless you've already created all the partitions you need. After installation, Vista will automatically add the boot menu to choose between the 'Earlier Version of Windows' (XP) and 'Microsoft Windows Vista', and the final step is to now install Linux into the remaining space.

Linux is last

We've used Ubuntu and Kubuntu in our example, but the vast majority of Linux installations will recognise your Windows installations without any manual intervention.

Ubuntu has a version of GPartEd built into the installation process and Live CD so that you can use this to resize your partitions before installing XP if you want to. When you return to install Linux, you will need to make a minimum of two extra partitions for the Linux installation.

Linux needs a swap partition that's usually around twice the size of your installed memory, and you will also need to create a root partition for the operating system. Make sure this is formatted using the 'etx3' filesystem (normally selected by default), and it uses a mount point of '/' for root.

You might also want to create an extra partition for your user's home directories - this is a good idea if you're forever upgrading your Linux version as a separate home partition means you can leave this partition untouched (along with all your personal data) and reformat and overwrite the root partition.

Lots of Linux distributions will simply find any alternative OSes installed, and add entries for these into the Linux boot menu. But there's something that's out of place; your Linux installation will see the Windows Boot Menu as a single operating system, and add this to the Grub/Lilo menu at boot time.

It will appear as 'Windows Vista/Longhorn Loader', and selecting this option will launch Microsoft's Boot Menu - so there are two layers of menus to use when booting into Windows. Aside from this, things will work as you expect, and you can now choose between XP, Vista and Linux on the same difference - the best of all worlds!

The full version of this article appears in issue 261 of PC Plus magazine.

Windows VistaMicrosoftComputingUpgradesSoftware
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