(this is a guide that was written to help people who wanted to install Red Hat via RULE as a second Os)
In this section it is assumed that the reader understands the terminology and concepts involved in hard disk partitions. An excellent introduction to the topic is the corresponding Mini Howto from the Linux Documentation Project.
The ideal situation for installing any new operating system on a computer, is when it is the only to be installed. The second most favorable situation is to be able to dedicate an entire disk to the new operating system. In all other cases we must share a hard disk between two or more operating systems. Usually, this would mean that one would need to delete the old partition(s) and then recreate them, leaving enough room for the new partition(s) for the new operating system. This results in the loss of all data currently stored on that hard disk.
It is possible to non-destructively repartition your current hard drive to create space for a RULE installation. However, finding the right tool for the task can often be difficult, and involves a trade off between cost and convenience. Be aware, as always, that manipulating your disk’s partition table and Master Boot Record is RISKY BUSINESS and you should have both current backups of critical data as well as a bootable floppy disk that will let you access the system to straighten things out should it go poorly. From a Microsoft Windows setup it is also advisable to defragment the partition first so as to gain as much free space at the end of the partition as possible.
If you think this is something you wish to do, first make sure that you have sufficient free storage on your existing partition(s) to hold a RULE installation. If you are using a version of Microsoft Windows, you can click the secondary button on the mouse (usually the right button of a two-button mouse, if you are right-handed) while the cursor is over the icon for the hard disk or hard disk partition. This will open a menu, from which you can choose “Properties” at the bottom. The result is a graph showing you how much storage is used, and how much is available, on that partition. If you are using Gnu/Linux or another Unix-like OS, from a shell prompt, type the command
df -k
This will report how much unused storage you have available on the disk, and in which partitions it is located. A workable, minimal RULE installation can be done in about 300 or 350 MB. 500 MB should be enough for XWindow and a window manager. Less than this, and you should probably not start the process.
Next, perform your backups if you have not done so, and either create a boot floppy from your current installation, or acquire one of the numerous pre-made boot/root rescue disks that various people have made available on the ‘Net. A suitable one is the (R)ecovery (I)s (P)ossible Linux rescue system. Note that there are a LOT of rescue disks here – take your time and decide which you like.
Now, you are ready for repartitioning of the drive. Here is where you have to decide which tool to use. Google has a page dedicated to partitioning tools. The tool you choose must support the type of file system(s) currently on your hard disk(s). So, if your existing partition is Gnu/Linux using the ext2 file system, you must use a tool that can resize ext2-based partitions. If you are using Windows 2000, you must use a tool that resizes NTFS5 partitions. Some of the commercial products shown on this page (for example Partition Magic) can handle just about every situation and provide a friendly graphical interface. However, they also cost real money, and often have restrictive licensing terms you may find disagreeable. Similarly, make sure you understand the limitations of each tool.
Currently, the GNU tool [parted->http://www.gnu.org/software/parted/parted.html] is not able to move the start of an ext2 partition. If you have sufficient space for a RULE installation, but it is spread over multiple partitions, then you may find it difficult or impossible to use parted to create a single, continuous block of free space on your hard drive for a RULE installation. Ideally, you would like to have all of the free space available at the end of the drive, otherwise you will need to make
adjustments to the current installation to allow for the new partitions that have appeared on the hard drive. For a Gnu/Linux installation, this means editting your /etc/fstab file to adjust the description of the relationship between mount points and partitions. For a Windows installation, it may require something as drastic as editing the Registry.