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FDisk - the Microsoft Partition Tool

FDisk is probably the original HDD partitioning utility; I believe it has been around as long as PC HDD's have. It is a DOS utility program that supports basic HDD partitioning functions for the Microsoft (and compatible) world only. FDisk is only distributed with DOS/W95/W98/W98SE/WME, and its use outside of those environments is not recommended unless you understand its limitations.  Support for NTFS partitions is limited to the ability to delete them if they are not in an extended partition.

FDisk is functional but not pretty. Some find its DOS, character-based interface to be antiquated, and a bit less user-friendly than the GUI interfaces they've come to expect these days.  FDisk operation is generally destructive to all data that resides in the partitions it operates on (Display Partition Information and Set Active Partition are the exceptions in this case).

FDisk provides no support for changing the size and type of existing partitions.   To resize a partition, it must first be deleted and then a new partition can be created with the desired new size.

FDisk Operation

If you're going to use FDisk, make sure you have the correct version if your disk is larger than 64 GB.  Although the larger-than-64GB version of FDisk will support disks of greater than 100GB (up to 137 GB), it does not provide support for larger than five-digit size specifications.  Sizes greater than 100 GB must be specified by using the percentage of the drive for the partition rather than the specific size.

Pre Windows 95C (OSR2) versions of FDisk only supported FAT 16 partitions, which were limited to 2 GB in size, and generally does not support physical drives larger than 8 GB.   FDisk should only be used in configurations consisting solely of FAT partitions for use by Microsoft operating systems.  If you are going to have any non-FAT or non-Microsoft partitions on a disk, it is recommended that you use the disk management utilities associated with those environments to create and maintain your disk. FDISK should be used only from native/real MS-DOS mode--NOT from a Windows DOS prompt (full screen from Windows is not native/real mode.) Backup all your data before using FDISK

When first started, FDisk should display the Large Disk Support warning.

Screenshots - Click here for step-by-step FDISK screenshots that show what the interface looks like.

Figure 1
Large Disk Support Warning

You definitely do want to select "Y" for "Yes" to enable this support. Following the warning screen you will be presented with the Main Menu.

Figure 2
FDisk Main Menu

Option 5 is the one to use to get to the Disk Selection Menu so that you can select which disk you want to work with.

Figure 3
Disk Selection Menu

For a new disk you would choose Create DOS Partition or Logical DOS Drive from the main menu.

Figure 4
Create Partition or Logical DOS Drive Menu

When you select the type of partition to create, you will be asked to provide information on the size of the partition and the file system type to be used, FAT16 (2GB or less only) or FAT32.

FDisk does not support any partition resizing activities; if you need to make changes to existing partitions, then you will need to visit the "Delete DOS Partition or Logical DOS Drive" menu. Operation from this menu is pretty straight-forward. You must first delete all logical DOS drives before deleting the Extended DOS Partition they live in.

Figure 5
Delete DOS Partition or Logical DOS Drive Menu

This menu is also the first place that we see any support for 'foreign' partitions. FDisk will recognize (some) non-DOS partitions if they exist on the drive. Although you can't create them, you can try to delete them. I don't believe FDisk is always completely successful when working with non-DOS partitions.

Option 4, from the FDisk Main Menu, will display the partition information for the currently selected disk drive (Fixed disk drive 1 = Physical drive 0) with a bootable primary partition and DOS Extended partition and its logical drives.

Figure 6
Display: A primary drive with bootable primary and extended partitions

Figure 7
Display: Logical volumes in the extended partition from Figure 6

In the figures below, the secondary drive (Fixed disk drive 2 = Physical drive 1) is displayed, showing an extended partition only and the logical drives contained in that extended partition.

Figure 8
Display: A secondary volume with an extended DOS partition only

Figure 9
Display: Logical volumes in the extended partition from Figure 8

The only remaining option (Option 2 from the main menu) is Set Active Partition. This is used to set the partition on the disk that is considered active (remember, there can be only one active partition on a disk). This is another place where non-DOS partitions will show up if they exist.

Figure 10
Set Active Partition menu

Well, there you have it, the basic partitioning operations using FDisk. Enjoy.

Bill

FDISK Links

Microsoft KB 255867: How to use FDisk and Format

Microsoft KB 263044: FDisk does not recognize disks larger than 64 GB

Microsoft's New FDisk Download: FDisk for Windows 98 that supports larger than 64 GB

Microsoft KB 245213: FDisk limits non-DOS partition end to 8 GB

Microsoft KB 243450: ScanDisk errors on IDE hard drives larger than 32 GB

Microsoft KB 261473: Unable to delete NTFS logical DOS Drive using FDisk

Microsoft KB 263045: Format displays size of partitions larger than 64 GB incorrectly

Microsoft KB 243450: ScanDisk errors on IDE hard drives larger than 32 GB

Microsoft KB 246818: Windows 95 (and its FDisk) does not support HDD larger than 32 GB

Microsoft KB 250270: Cannot start WNT on Partition Magic Dual Boot after upgrade to W98

Microsoft KB 249085: (W2K) Delete primary partition without removing extended partition.

Microsoft KB 149877: Boot Record Signature AA55 not found.