6.0

Appendix A. Partitions and File Systems
A.1 Hard Disk Partitions
It would be quite inconvenient if you could only access the entire hard disk,
so a mechanism was created that allows you to divide the hard disk into
several parts for storing different types of data or operating systems. This is
done by partitioning hard disks into partitions.
Partitioning hard disk is done by special applications. In MS-DOS and
Windows the widely known FDISK and Disk Administrator programs are used
for this purpose. They allow creating partitions, setting their size and labels.
Partitioning programs can perform the following functions:
create a Primary Partition (up to 4);
create an Extended Partition that can be divided into any number of
logical disks;
mark a partition as active (only one primary partition can be active).
Information about partitions on a hard disk is stored in a special disk area – in the 1
st
sector of the 0
th
cylinder, header 0, which is called a Partition Table. This sector is
called the Master Boot Record, MBR.
A physical hard disk can contain up to 4 primary partitions. This limitation is due
only to the capacity of the Partition Table, which itself consists of only four
partitions. However, this does not mean that you can install only 4 different
operatin
g
systems. Modern software disk mana
g
ers allow the installation of many
more operating systems. For example, the Acronis OS Selector 5.0 Deluxe disk
manager to install up to 100 operating systems on one hard disk!
A.2 File Systems
An operating system provides the user with ability to work with data by
supporting some type of file system on a partition.
All file systems are made of structures that are necessary to store and
manage data. These structures are usually comprised of operating system
boot sectors, folders, and files. File systems perform the following basic
functions:
1. track occupied and free disk space (and bad sectors, if any);
2. support folders and file names;
3. track physical location of files on disks.
36 Appendix A : Partitions and File Systems