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Q117131: Master Boot Record Not Written to Mirrored Shadow Partition

Article: Q117131
Product(s): Microsoft Windows NT
Version(s): 3.1,3.5,3.51
Operating System(s): 
Keyword(s): kbother
Last Modified: 08-AUG-2001

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The information in this article applies to:

- Microsoft Windows NT Advanced Server, version 3.1 
- Microsoft Windows NT Server versions 3.5, 3.51 
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SYMPTOMS
========

After you make the previously shadowed partition of a mirrored system partition
into the primary partition, when you restart your computer, it stops responding
(hangs). Only the initial system and peripheral BIOS startup text is displayed
on the monitor.

CAUSE
=====

Windisk is the utility that manages disk partitioning in Windows NT Server. When
it establishes a mirrored partition on a previously unused disk, it does not
check for the existence of valid boot code in the Master Boot Record. At
startup, the system BIOS of an Intel 80x86-based computer expects the Master
Boot Record to contain executable code which is responsible for locating and
passing control to the boot sector on the active partition. When this code is
not present, the processor attempts to execute random memory and the computer
hangs.

NOTE: If the disk used to hold the shadow of the mirrored system partition was
previously partitioned, either by Windows NT Server, MS-DOS, or any other
operating system which uses the same partitioning scheme, the Master Boot Record
will already contain valid boot code and the system will boot successfully when
started from the former shadow partition. Only when the secondary disk was not
previously partitioned will this result in your computer hanging.


WORKAROUND
==========

Through the use of a Windows NT "boot floppy", the operating system can still be
initialized. For information on how to create such a floppy, see pages 161 and
162 of the "Windows NT Advanced Server Concepts and Planning Guide," or see the
following article in the Microsoft Knowledge Base:

  ARTICLE-ID: Q119467
  TITLE : Creating a Boot Disk for an NTFS or FAT Partition


It is possible to initialize the boot code in the Master Boot Record by using
WINDISK.EXE to modify the disk partition structure. When you manually make and
format a primary partition Windisk.exe will initialize the master Boot Records
boot code.


STATUS
======

Microsoft has confirmed this to be a problem in the Microsoft products that are
listed at the beginning of this article.

Additional query words: prodnt repair tshoot fdisk mbr

======================================================================
Keywords          : kbother 
Technology        : kbWinNTsearch kbWinNT351search kbWinNT350search kbWinNTSsearch kbWinNTS351 kbWinNTS350 kbWinNTAdvSerSearch kbWinNTAdvServ310 kbWinNTS351search kbWinNTS350search kbWinNT310Search
Version           : :3.1,3.5,3.51

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