Installation guide

Figure 25.5. Disk Drive with Partition Table
As Figure 25.5, “Disk Drive with Partition Table” shows, the partition table is divided into four
sections or four primary partitions. A primary partition is a partition on a hard drive that can con-
tain only one logical drive (or section). Each section can hold the information necessary to
define a single partition, meaning that the partition table can define no more than four partitions.
Each partition table entry contains several important characteristics of the partition:
• The points on the disk where the partition starts and ends
• Whether the partition is "active"
• The partition's type
Let us take a closer look at each of these characteristics. The starting and ending points actu-
ally define the partition's size and location on the disk. The "active" flag is used by some operat-
ing systems' boot loaders. In other words, the operating system in the partition that is marked
"active" is booted.
The partition's type can be a bit confusing. The type is a number that identifies the partition's an-
ticipated usage. If that statement sounds a bit vague, that is because the meaning of the parti-
tion type is a bit vague. Some operating systems use the partition type to denote a specific file
system type, to flag the partition as being associated with a particular operating system, to indic-
ate that the partition contains a bootable operating system, or some combination of the three.
By this point, you might be wondering how all this additional complexity is normally used. Refer
to Figure 25.6, “Disk Drive With Single Partition”, for an example.
Figure 25.6. Disk Drive With Single Partition
In many cases, there is only a single partition spanning the entire disk, essentially duplicating
the method used before partitions. The partition table has only one entry used, and it points to
the start of the partition.
1.2. Partitions: Turning One Drive Into Many
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