MORE INFORMATION
Microsoft does NOT guarantee the ability to start from a
mirrored drive without the use of a Windows NT Fault tolerant boot disk. This
is because Windows NT mirrors partitions and information contained in the Bios
parameter block in the master boot sector of the partition on the primary drive
may not be valid for the partition we are mirroring to on the shadow drive. The
bios parameter block contains vital information required for starting and is
partition specific.
For more information, click the following article number to view the article in the Microsoft Knowledge Base:
119467
How to create a bootable disk for an NTFS or FAT partition
In many cases, booting from the shadow drive works,
but this is dependent on the following requirements:
- Both the primary drive and shadow drive MUST be identical
in make, model, and in many cases firmware revision. This is to ensure that the
drive geometry is identical and is being translated identically.
- Both the primary and shadow drive must be attached to
identical controllers with the same BIOS and Firmware revisions. Both
controllers must have translation options set identically - either both enabled
or both disabled.
- Both the primary and shadow drive must be identically
partitioned for the location of the operating system partition and partitions
before the operating system partition must also be identical. If an EISA
partition exists on the primary drive, an identical partition must exist on the
shadow drive.
- The shadow drive must contain a primary partition that is
marked active and contains a valid Boot.ini file along with NTLDR and
Ntdetect.com.
- The primary drive must be inaccessible or disconnected
while you start Windows NT again using the shadow drive or a STOP 0x1E
occurs.
- The shadow drive must contain valid boot code in the Master
Boot Record (MBR).
Failing to meet ANY of the above requirements may prevent
booting into Windows NT from the shadow drive.
Possible Problems and Solutions
Problem:
The primary and shadow drives are not identical. Geometry or
firmware revision differences cause the drive to be translated differently.
Solution:
Ensure drives are identical. To check firmware revision of the
same manufacturer and model disk drive, perform the following
steps:
WARNING: If you use Registry Editor incorrectly, you may cause serious
problems that may require you to reinstall your operating system. Microsoft
cannot guarantee that you can solve problems that result from using Registry
Editor incorrectly. Use Registry Editor at your own risk.
- Run Registry Editor (Regedt32.exe) and go to the following
subkey:
HKEY_LOCAL_MACHINE\HARDWARE\Devicemap\Scsi\ScsiPort<x>\ScsiBus<x>\TargetId<x>\LogicalUnitId<x>
where x varies according to device number.
- Look at the REG_SZ identifier value to see the model number
and firmware revision values. For example, if you see the following REG_SZ
identifier value0510 is the firmware revision value.
Problem
The controller that contains the shadow drive had its BIOS
disabled and the translation being performed is now different from the original
Primary drive.
Solution
Many SCSI Bioses disable translation mode if the bios is
disabled. This prevents the drives attached to the SCSI controller from being
translated and effects the boot process. Ensure BOTH SCSI controllers have
their BIOS and translation options set the same.
Problem
The primary drive had an EISA partition in front of the system
partition and you mirrored to a drive that did not contain an EISA partition.
Solution
Before you mirror to the shadow drive, make an identically-sized
EISA partition. It may be possible to move the shadow drive to another Windows
NT computer to modify the MBS Hidden Sector value by using the Windows NT 4.0
resource kit utility Dskprobe.exe to make it bootable.
165181 EISA configuration boot code is replaced on mirror drives
Problem
The Primary partition on the shadow drive is not marked active.
Solution
Use one of the following methods to mark the a partition active.
- Run the MS-DOS FDISK utility and make sure you have an
active partition.
- Use Disk Administrator/Management to mark the partition
active.
Problem
When you boot from the shadow, you receive a STOP 0X0000001E error
message.
Solution
This behavior occurs because primary drive is still accessible.
This causes a stop 0x0000001E error message while entering kernel mode. To
resolve this behavior, disable the primary drive by either unplugging the power
or the SCSI connector.
For more information, click the following article number to view the article in the Microsoft Knowledge Base:
141242
STOP Msg: 0x0000001E testing new fault tolerance boot disk
Problem
After you make the previously shadowed partition of a mirrored
system partition into the primary partition; when you restart your computer, it
stops responding. Only the initial system and peripheral BIOS startup text is
displayed on the monitor.
Solution
The shadow drive was mirrored to as a raw drive so the Intel boot
code was never initialized on sector 0. Prior to mirroring, Use Disk
Administrator to make and format a primary partition. Then delete the new
partition to make free space. This procedure ensures the Intel boot code is
placed on sector 0.
How To Guarantee Booting from the Shadowed Drive
If you have a primary drive failure, using the fault tolerant boot
floppy disk always enables you to boot to the shadow drive because you are
relying on the floppy disk drive to act as the boot device. This works because
the computer is not relying on the shadow drive's boot partitions BIOS
parameter block in the master boot sector to locate and load the NTLDR and
Boot.ini files. If you then maintained a small bootable FAT partition at the
beginning of the shadow drive to act as the boot partition, it would, in
effect, take the place of the fault tolerant boot floppy (by loading the NTLDR
and boot.ini files and displaying the boot menu). This small FAT partition can
be made prior to establishing the mirror on the shadow drive and take the place
of the EISA partition if one is located on the primary drive.
Because the shadow drive must contain enough free space to contain the
operating system partition you are mirroring, you need to plan this scenario
ahead of time and, if necessary, make the same size small FAT bootable
partition on the primary drive prior to installing Windows NT. This will ensure
you can always boot from the primary or shadow drive.
For additional information, click the article number
below to view the article in the Microsoft Knowledge Base:
138364 Windows NT Partitioning Rules During Setup
It may be necessary to pre-partition the drive
prior to installing Windows NT in order to get 2 primary partitions created.
This can be accomplished by moving the drive to another computer running
Windows NT and use Disk Administrator to create 2 primary partitions. This is
because MS-DOS FDISK will not allow you to create a second primary partition.
If the primary partition fails to boot, you can run MS-DOS FDISK and
mark the small FAT partition as the active partition so you have 100 percent
boot backup without the need of a Windows NT boot floppy disk.
|---------------------- EXAMPLE NUMBER 1 ----------------------|
|--------------------------------------------------|
DISK-0 | FAT PRIMARY | * NT OS on 2nd PRIMARY Partition |
PRIMARY | (backup boot)| SET ACTIVE |
|--------------------------------------------------|
|--------------------------------------------------|
DISK-1 |* FAT PRIMARY | SHADOW DRIVE |
SHADOW | SET ACTIVE | of NT OS |
|--------------------------------------------------|
|---------------------- EXAMPLE NUMBER 2 ----------------------|
|--------------------------------------------------|
DISK-0 | EISA | * NT OS on PRIMARY Partition |
PRIMARY | PARTITION | SET ACTIVE |
|--------------------------------------------------|
|--------------------------------------------------|
DISK-1 |* FAT PRIMARY | SHADOW DRIVE |
SHADOW | SET ACTIVE | of NT OS |
|--------------------------------------------------|
Note: Make sure the ARC path is set correctly in the Boot.ini files
located on the FAT partitions.