Reference number: CH000226

Partition shows up as a MS-DOS partition.

Issue:

Partition shows up as a MS-DOS partition.

Cause:

Below are reasons why a partition may show up as a MS-DOS partition in fdisk.

1. A DDO or Disk Drive Overlay is being used.
2. Windows NT or other operating system is installed that does not utilize FAT (File Allocation table).
3. Partition was setup as a MS-DOS partition.
4. A save to partition utility such as phdisk is present on the hard disk drive.
5. Computer virus is present on the computer.

Solution:

A DDO or Disk Drive Overlay is being used.

A DDO or Disk Drive Overlay is a TSR that loads onto sector two of the hard drive used for computers that do not support LBA mode that allows your computer to support and see larger then 520 MB. A DDO can also be used to setup a hard disk drive on a computer. When booting from a bootable diskette and your partitions are displayed as a MS-DOS partition it is likely that a DDO is present on the computer.

To verify if a DDO is present on the computer, remove all diskettes from the computer and as the computer is booting see if any message appears asking you to press a key sequence such as CTRL + ESC to boot from a diskette. If this message is displayed or a similar message it is likely that a DDO is loading. 

To see the partitions correctly, wait for this message and press the key sequence once asked to boot from a diskette. Once the appropriate keys are pressed the computer will prompt you to then insert the bootable diskette.

Windows NT or other operating system is installed that does not utilize FAT (File Allocation table).

If a partition that does not use the FAT system is loaded into the computer, FDISK will display the partitions as a MS-DOS partition. Operating Systems that do not apply to this rule are: MS-DOS 5.0 and above, Windows 3.x, Windows 95, Windows 98 and Windows ME. If any other operating system has been loaded onto the computer it is likely that a different file structure is being used such as NTFS or HPFS. 

Partition was setup as a MS-DOS partition.

If a partition has been setup through Fdisk as a MS-DOS partition it will then be displayed as a MS-DOS partition. If you have not setup the partition to be a MS-DOS partition see other possibilities. 

If you have created a partition in Fdisk as MS-DOS partition use Fdisk to delete that MS-DOS partition and recreate the partition as a Primary or Extended Logical partition.

Important: If you are currently running an installed copy of MS-DOS 5.0 and above, Windows 3.x, Windows 95, Windows 98 or Windows ME, it is likely that the partition was not setup as a MS-DOS partition

A save to partition utility such as Phdisk is present on the hard disk drive.

If your computer is a laptop computer and using Windows 3.x, Windows 95, Windows 98 or Windows NT it is possible that your computer may be using a save to file utility such as Phdisk. This utility is designed save information you may be working on when it goes into sleep mode or when your battery becomes low on power. Generally, this partition will be a small section of the hard disk drive and you should have another partition setup as a Primary or Extended Logical that contains your operating system.

If you do not have a laptop or all partitions are being displayed as a MS-DOS partition refer to another possibility.

Computer virus is present on the computer.

If you believe that none of the above possibilities are causing your computer to be displayed as a MS-DOS partition it is likely that the computer may be infected by a computer virus. If you have a virus scanner verify it is up-to-date and that you scan your computer for any viruses that can be cleaned on the computer.

If you do not have a virus protection program on the computer or cannot obtain an up-to-date virus scanner it is recommended that you use fdisk to delete and then recreate your partitions on the hard disk drive.

Additional information:

• See our fdisk command page for additional information about this command.