A.4 Primary Partitions
Primary hard disk partition can contain operating system, applications and
user data (files). Only one primary partition can be set active in the given PC
session.
Most operating systems can boot from a primary partition only.
If you want to use several operating systems, you might have to create sev-
eral primary partitions.
A.5 Extended Partitions
The extended hard disk partition was offered as a way to avoid the 4 primary
partitions limit. Extended partition is used only for creating a desired number
of logical partitions.
Extended partition may not contain any data directly.
A.6 Logical Partitions
Extended partition can be divided into any number of logical partitions that
are similar to primary partitions. In particular, they can contain operating
systems, applications, and user data.
Primary partitions should be used for booting operating systems and system
files and folders.
Logical partitions may contain any other information, as they are accessible
by most operating systems.
If you need several operating systems, you should use logical partitions for
those which can boot from them, and leave primary partitions free.
A.7 Formatting Hard Disks
Within each of the partitions information has to be organized in a way under-
standable for the operating system that uses the partition. This organization
is the file system.
As a rule, formatting program performs the following functions:
• It creates the boot record;
• It creates the file allocation table (FAT);
• It marks bad clusters so they are not ever used afterwards.
70 Appendix A : Hard Disk And Operating System
