Preparing a Hard Drive

Step 2 - Partition Types

There are two types of partition that FDISK can create - Primary and Extended.

Primary

• Can be Bootable.
• Can occupy all of the space on a drive when present in either a single or multiple drive system.
• Can occupy some of the space on a drive if sharing with other Primary or Extended partitions.
• Can occupy none of the space on a drive if the entire drive has been allocated as an extended partition (Another Primary partition would have to exist if this were the case).
• On single drive systems, you must have a Primary partition present on the drive.
  

Extended

• Non bootable.
• Can occupy all drive space if present in a two drive system (a Primary partition must be present elsewhere in the system).
• Can occupy some of the space on a drive along with other Primary and/or Extended partitions.
• May not be present on a single drive system if a Primary partition is present and using all the space on the drive.

Drive Letter Allocation

It is worth taking some time to understand how FDISK allocates space and drive letters, particularly if you are adding an additional drive because you may alter the drive letters allocated to an existing drive which could cause problems if software is registered to these drive letters.

The following example shows a typical multi drive system and the allocation of the Primary and Extended partitions.

In this example the Primary partition could be a physical drive partitioned as logical drive C: and the Extended partition could be a second physical drive, partitioned into logical drives D: and drive E:

Alternatively this could be one physical drive partitioned into three logical drives C:, D: and E:

Got the picture? Good.

Let us assume for our exercise that the example shown in the table above is a system with a single physical drive - Drive 1, partitioned into three logical drives C:, D:and E:

If we wanted to add a new physical drive (Drive 2) to the system which contained a Primary partition, FDISK would allocate it the logical drive letter D:
FDISK would rename the old logical partitions D: and E: allocating them the logical drive letters E: and F:

The system would now be set up as below...

This would cause problems with any software that was registered to the old logical drives D: and E: as they are now drive E: and F:

To avoid this situation we could allocate the new drive as an Extended partition which would allocate the drive letters as follows...

If this is a completely new system with no data on any of the drives or if you are formatting all partitions to start afresh, you may be happy to simply let the second drive be named D:
However, why allocate Drive 2 as a Primary partition when it cannot be bootable anyway. It can be fully formatted as an extended partition if Drive 1 has a Primary partition on it.