Red Hat ENTERPRISE LINUX AS 2.1 Installation Manual page 199

Section F.1:Hard Disk Basic Concepts
• A root partition ( / ) — The root partition is where / (the root directory) resides. In this partitioning
layout, all files (except those stored in /boot) reside on the root partition. Because of this, it is in
your best interest to maximize the size of your root partition. A 1.0 GB root partition will permit
the equivalent of an Advanced Server installation (with very little free space), while a 3.2 GB
root partition will let you install every package. Obviously, the more space you can give the root
partition, the better.
Specific recommendations concerning the proper size for various Red Hat Enterprise Linux AS parti-
tions can be found in Section 1.5, Which Installation Class is Best For You?.
F.1.9 One Last Wrinkle: Using GRUB or LILO
GRUB and LILO are the most commonly used methods to boot Red Hat Enterprise Linux AS on Intel-
based systems. As operating system loaders, they operate "outside" of any operating system, using
only the Basic I/O System (or BIOS) built into the computer hardware itself. This section describes
GRUB and LILO's interactions with PC BIOSes and is specific to Intel-compatible computers.
BIOS-Related Limitations Impacting GRUB and LILO
GRUB and LILO are subject to some limitations imposed by the BIOS in most Intel-based computers.
Specifically, most BIOSes cannot access more than two hard drives, and they cannot access any data
stored beyond cylinder 1023 of any drive. Note that some recent BIOSes do not have these limitations,
but this is by no means universal.
All the data GRUB and LILO need to access at boot time (including the Linux kernel) is located in
the /boot directory. If you follow the partition layout recommended above or are performing an
Advanced Server install, the /boot directory will be in a small, separate partition. Otherwise, it may
reside in the root partition (/). In either case, the partition in which /boot resides must conform
to the following guidelines if you are going to use GRUB or LILO to boot your Red Hat Enterprise
Linux AS system:
On First Two IDE Drives
If you have 2 IDE (or EIDE) drives, /boot must be located on one of them. Note that this
two-drive limit also includes any IDE CD-ROM drives on your primary IDE controller. So, if
you have one IDE hard drive, and one IDE CD-ROM on your primary controller, /boot must
be located on the first hard drive only, even if you have other hard drives on your secondary IDE
controller.
On First IDE or First SCSI Drive
If you have one IDE (or EIDE) drive and one or more SCSI drives, /boot must be located
either on the IDE drive or the SCSI drive at ID 0. No other SCSI IDs will work.
On First Two SCSI Drives
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