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What Is A Partition?
As you can probably guess by breaking
down the word partition, it's a 'part' or section of the
hard disk, although that's a bit misleading because 'part'
tends to indicate that a partition is less than 100% of the
drive. Although a partition 'can' be less than 100% of the
space available on a drive it doesn't have to be less. As a
matter of fact a hard drive can exist perfectly well on a
system without any partition(s) on it whatsoever; it just
won't be of any value for accessing and storing data. I
think it's a bit more accurate to look at partitions as
defining a certain area or amount of space on a hard drive,
be it 1 or 100% of the drives total capacity.
Partition Types
Depending on
type of system and
what operating system is being used there are many different
types of partitions, but since this site deals with XP it's
most likely you'll be dealing with two types of partitions;
Primary and Extended. Depending on who you ask, some people
consider logical drives as another type of partition. To me,
this is more a case of semantics than anything else, but
I've included Logical Drives in this section.
Primary Partition
- A partition that is used to start an operating system,
although you can use primary partitions that don't
contain the operating system. Look at the color coded
key at the bottom of Fig. 01 and you'll see that Primary
partitions are denoted by the dark blue color.
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There can be up
to a maximum of four primary partitions on a single
basic disk.
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The Primary partitions do not have to
come before Extended partitions as shown on Disk 0.
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A drive is not required to have any
Primary partitions as shown by Disk 1
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CD-ROM 1, while
it does contain a blank CD, is not shown as containing a
partition because there is no data contained on the CD.
Fig. 01
Extended Partition
- A partition that can be sub-divided into logical drives.
Look at the color coded key at the bottom of Fig. 01 and
you'll see that Extended partitions are denoted by the dark
green color.
- An extended
partition is not formatted or assigned a drive letter.
- It's essentially
a container for logical drives that are formatted and
assigned drive letters. Disk 0 and 1 contain extended
partitions that have a green band surrounding the
logical drives (discussed below) that have been created
in the extended partition.
Logical Drive
- A logical drive is created within an extended
partition. Look at the color coded key at the bottom of
Fig. 01 and you'll see that Logical drives are denoted
by the lighter, bright blue color.
- An "unlimited"
number of logical drives may be created in an extended
partition, formatted and assigned drive letters.
Unlimited is another misleading term used in conjunction
with logical drives. The reality is you're limited by
the number of available drive letters and the amount of
hard drive space available for creating drives. In Fig.
01, Disk 1 has two logical drives, F and G, identified
by the bright blue color and contained within the
extended partition. More Logical drives could be created
in the Free Space until you either ran out of drive
letters or the Free Space was exhausted.
- Disk 1 and 2 also contain
Unallocated space that isn't assigned to either a
primary or extended partition. I'll deal with
unallocated space later in the article.
System and Boot Partitions
This seems like as good a time as any for
a brief discussion of System and Boot partitions. In almost
every case where I've attempted to explain the difference
between System and Boot partitions people have walked away
shaking their heads because it just doesn't make any sense,
but I'll give it another try. Here we go;
- Whenever a computer system is
started, either from a cold boot using the power switch
or a warm boot such as restarting the system from within
Windows, there are certain files needed to boot (start)
the computer. These boot files reside on the System
partition.
- Once the boot files have been
accessed and performed their function, the system files
(the files that comprise the XP operating system) are
accessed to complete the system start. The system files
reside on the Boot partition.
If you just accept these two statements
are true then everything will be fine. I know it makes no
sense and seems to defy logic, but it's true.
The boot files reside on
the System partition ---
The system files reside on the Boot partition
Fig. 02
Look at Fig. 02 and you'll
see C: is designated as the System partition. There is no
designated Boot partition. In most cases this is the
standard setup and there won't be a separate Boot partition
designated.
Look at Fig. 03 and you'll
see C: is designated as the System partition and I: is
designated as the Boot partition. The boot files are located
on partition C: and the system files (the XP operating
system) are installed on the I partition.
Both screen captures are of
the identical system so why does one have the Boot partition
uniquely identified? The answer is because there are two
operating systems installed on the same machine, or what is
often called a dual boot setup. Windows XP is installed on
drive C: and Windows XP is also installed on drive I:. When
the system is set to boot from the operating system
installed on partition C: the system and boot files reside
in the same partition so there is no need for a separate
Boot partition designation. When the system is set to boot
from the operating system installed on partition I: the
system and boot files reside on different partitions so
partition I is designated as the Boot partition.
Fig. 03
There is one more term that
you may occasionally run across and that's Active partition.
Any primary partition that has an operating system installed
on it may be designated as the Active partition simply for
the sake of convenience in making it the System partition.
Active partition and System partition mean the same thing.
Next: One Partition or Multiple
Partitions ? --->>
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