A lot of confusion to people doing their first install of Linux comes from the partitioning of the drives. This article is intended to show you the basics of setting up your harddisk for a dual boot installation of Linux and Windows. Here I assume you are using regular old IDE drives, things will change for scsi and the like.
Physical Disks and Logical Disks
Harddrives can be broken down into an abstract hierarchy using various techniques, such and raid. Here we will be looking at, and using only 2 part of that structure, the physical and logical disk.
The Physical Disk is the actual physical drive you can hold in your hand and plug into your computer. When using IDE you will generally have room for four physical disks. This will include harddrives and DVD/CD drives.
Using partitions you can create several logical drives on one physical drive. The logical drive will be basically what the operating system sees.
How Windows Sees Things
You are probably familiar with C: D: and whatnot drives. Usually C: will be first partion of the first physical disk. D: is usually the CD drive unless there is another disk or partition in front of it. A: and B: are usually reserved for floppy disks. Under XP administrative settings you can see how your physical disks are partitioned and what drives are assigned to what letter.
How Linux Sees Things
Linux stores all the interfaces to devices as files. The /dev directory usually holds most of them. The first physical device will be known as /dev/hda, the second as /dev/hdb. The interface to each partition of a physical device will be the physical device name followed by the partition number (ex: /dev/hda1 is first physical disk, first partition).
Preparing For A Linux Installation
The easiest thing to do would be getting a second harddrive for Linux to live on. However, other methods include using partition magic or wiping the harddrive and reinstall Windows after it has been partitioned.
We will be discussing using one physical disk to reinstall Windows, then install Linux. Order is important here. If you install Windows second, it will overwrite the MBR and not tell anyone, forcing you to reinstall a Linux bootloader such as Grub. If you are new to Linux, that is no fun.
A good format is always good for Windows so we will start with that. Either using the rescue console mode of the Windows CD, an old Win9x boot floppy, or the install media of linux run fdisk. Delete all partitions on the disk and create a new one however big you want Windows to be. Remember Linux will usually need about 2 gigs to install the OS and applications, and you may also want user space to play with. Apply the chages to fdisk and install Windows on the partition you created.
Most Linux installs (ie. Fedora Core) will have an option to use free space on the physical drive. It will then usually create 3 partitions.
- / : / is the root of the Linux directory structure. Much like the \ in C:\. However many filesystems can be mounted under /. (This would be kind of like C:\harddrive2\D:\ where you could access the D: drive from within C: instead of from My Computer). This partition is the meat of your Linux install. All programs and user files will be stored on this drive.
- # /boot : This partition will hold the Bootloader (usually Grub) and the kernel and other things required to boot. The partition will be attached to system as /boot
- SWAP : Swap is a partition used as virtual memory when you run out of RAM. It is usually recommended to be twice the size of the RAM you have installe