Red Hat ENTERPRISE LINUX WS 2.1 Installation Manual page 90

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As with most computer-related technologies, disk drives changed over time after their introduction. In
particular, they got bigger. Not larger in physical size, but bigger in their capacity to store information.
And, this additional capacity drove a fundamental change in the way disk drives were used.
D.1.2. Partitions: Turning One Drive Into Many
As disk drive capacities soared, some people began to wonder if having all of that formatted space
in one big chunk was such a great idea. This line of thinking was driven by several issues, some
philosophical, some technical. On the philosophical side, above a certain size, it seemed that the ad-
ditional space provided by a larger drive created more clutter. On the technical side, some filesystems
were never designed to support anything above a certain capacity. Or the filesystems could support
larger drives with a greater capacity, but the overhead imposed by the filesystem to track files became
excessive.
The solution to this problem was to divide disks into partitions. Each partition can be accessed as if it
was a separate disk. This is done through the addition of a partition table.
Note
While the diagrams in this chapter show the partition table as being separate from the actual disk
drive, this is not entirely accurate. In reality, the partition table is stored at the very start of the disk,
before any filesystem or user data. But for clarity, we will keep it separate in our diagrams.
Figure D-5. Disk Drive with Partition Table
As Figure D-5 shows, the partition table is divided into four sections. 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
•
Appendix D. An Introduction to Disk Partitions