Disk Administrator Does Not Set System Partitions Correctly

 Last reviewed: July 24, 1996
Article ID: Q151358
The information in this article applies to:
  • Microsoft Windows NT Workstation versions 3.5 and 3.51
  • Microsoft Windows NT Server versions 3.5 and 3.51

SYMPTOMS

In a dual-boot configuration, when you delete and re-create Windows NT file system (NTFS) partitions on the hard disk, extra drive letters appear when you boot to MS-DOS.

CAUSE

This is caused by Disk Administrator not setting the partition type correctly (the partition should be 06 for file allocation table [FAT] and 07 for NTFS). When the computer starts, the BIOS scans the master boot record (MBR), and when it finds the value 06 for the partition type, it assigns a drive letter.

RESOLUTION

You will need a sector editor such as Windows NT Diskedit or Norton Diskedit to resolve the issue. Using the sector editor, change the Partition type from 06 to 07. An example is shown below using Windows NT diskedit:

  1. Start Windows NT diskedit. On the file menu, select Open and type: 

                                \\.\physicaldriveX

    where X = the number in which the disk appears in Disk Administrator.

  2. On the Read menu, select Sectors and type 0 for the sector and 1 for the Run length. This will take you to the MBR, which contains the Partition table.

  3. Go to line 01C0, which contains the partition type for the first partition. These lines are arranged according to the order of the partitions; the first partition is 01C0, the second partition is 01D0, the third partition is 01E0, and so on. You will see something similar to the example below:

NOTE: this is a partial view of what will be on your screen. 

      01C0  01 00 06 FE....
      01D0  01 0D 07 FE....
      01E0  01 1A 06 FE....
      01F0  00 00 00 00....

   The first partition (01C0) is FAT, and the partition type listed is 06,
   which means FAT, so this entry is correct. The second partition (01D0)
   is NTFS, the partition type listed is 07, which is also correct. The
   third partition (01E0) is NTFS but the partition type listed is 06, or
   FAT. This is the entry you must change. Move your cursor to the number 6
   and change it to 7.

  • Go to the Write menu select Write it, and close Windows NT Diskedit. Boot to MS-DOS and verify the drive letter is removed.

    STATUS

    Microsoft has confirmed this to be a problem in Windows NT version 3.51. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

    • KBCategory: kbnetwork
    KBSubcategory: ntfilesys ntsrvwkst
    Additional reference words: 3.50 3.51 prodnt

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    Last reviewed: July 24, 1996
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