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How to fix Windows NT 4.0's 7.8 GB System Partition limitation
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Louis Ohland
Jan 4, 2015, 7:50:03 PM1/4/15
to
http://www.nu2.nu/fixnt4/
Introduction
If you replace a harddisk from a NT 4.0 machine using Symantec Ghost or
PowerQuest Drive Image, most of the time the new harddisk is a lot
bigger than the old one. Normally with NT 4.0 you have to "clone" the
NTFS system partition within the 7.8 GB limit. But not anymore...
This page will show you how you can use Windows 2000 or XP's bootsector,
ntldr and ntdetect.com to fix NT 4.0's 7.8 GB system partition limitation.
To pull this off you'll need a tool, mkbt.exe created by Bart Lagerweij.
For more information on mkbt check the mkbt page.
Mkbt.exe is used to extract or install FAT and NTFS partition boot
sector(s).
Technical
Although Windows NT 4.0 can in theory support partitions of up to 16
exabytes in size using the NTFS file system, the maximum size of the
system partition is limited to 7.8 gigabytes (GB).
What is the system partition?
The system partition is defined as the partition containing the files
needed for the initial system startup. For Windows NT, the files are
Ntdetect.com, NTLDR, Boot.ini, and sometimes Ntbootdd.sys
Why the 7.8 GB limit?
During the bootstrap process, Windows NT 4.0 uses INT13 BIOS functions
to access the drive. The INT13 functions have a maximum of 256 heads,
1024 cylinders, and 63 sectors. This is approximately 7.8 GB (512 bytes
per sector).
NOTE: Partitions other than the system partition are not affected by the
these limitations.
When trying to boot with ntldr located passed the 7.8GB limit you will
get this error message:
Os Loader V4.01
.Disk I/O error: Status = 00000001
Windows NT could not start because the following file is missing or corrupt:
\system32\ntoskrnl.exe.
Please re-install a copy of the above file.
More information about this:
Windows NT 4.0 Supports Maximum of 7.8-GB System Partition
Microsoft Knowledge Base Article - 224526
Windows NT Boot Process and Hard Disk Constraints
Microsoft Knowledge Base Article - 114841
Installation
The steps to fix NT4.0 are:
Download mkbt.exe from the mkbt page and put in on a floppy disk.
On a Windows 2000 or XP PC copy ntldr and ntdetect.com. They are
normally located in the c:\ folder and hidden. Copy them to a floppy
disk. Use mkbt.exe to extract the NTFS boot sector(s). A bootable NTFS
partition uses the first 16 sectors to store the bootstrap loader.
Use this command to extract the NTFS bootstrap loader and save it
to floppy disk:
mkbt -x -c c: a:\bootsect.bin
The -c option is for "copy" mode.
The -x option is for "expert" mode, in standard mode mkbt only
accepts floppy drives "a:" and "b:"
Goto to the "limited" NT 4.0 system, boot it and login as
administrator.
Rename the existing ntldr into ntldr.nt4
Rename the existing ntdetect.com into ntdetect.nt4
Copy the ntldr and ntdetect.com from the floppy disk on the NT 4.0
system partition, normally "c:\".
Use this command to make a backup of the current boot sector:
mkbt -x -c c: a:\bootsect.nt4
Use this command to install the NTFS bootstrap loader from floppy disk:
mkbt -x a:\bootsect.bin c:
If your NT 4.0 machine uses a fixed NT boot disk driver
ntbootdd.sys (will have "scsi" entries in your boot.ini) you must also
update that to a Windows 2000 or XP version.
Done. You can now reboot the system and see if it boot's up OK. With the
Windows 2000 or XP bootstrap loader your Windows NT 4.0 machine can have
a system partition of 2TB. This is the maximum partition value.
Remarks
THIS PROCEDURE IS PROVIDED "AS IS," WITHOUT WARRANTY OF ANY KIND,
USE AT YOUR OWN RISK!
For more information check the Nu2 license.
Don't mix languages. If you use Windows NT 4.0 English and you
install the bootsector, ntldr and ntdetect.com in Dutch language you
will get a kernel load error message.
Installing NT 4.0 Service Pack will overwrite the ntldr and
ntdetect.com! So you must update these files again!
I have tested the above on a Windows NT 4.0 machine with a 40GB
harddisk. I don't know if Microsoft supports this, so maybe you can get
into trouble whenever you talk to a Microsoft support engineer.
The second copy of the NTFS boot sector is not changed, maybe next
version of mkbt.exe will also update that. If your Windows NT 4.0
machine doesn't boot anymore because the boot files are located passed
the 7.8GB location on disk, you have 2 options:
Create a generic Windows 2000 or XP bootdisk on another machine
(see here) and boot it. Boot BartPE (Bootable CD-Rom).
Introduction
If you replace a harddisk from a NT 4.0 machine using Symantec Ghost or
PowerQuest Drive Image, most of the time the new harddisk is a lot
bigger than the old one. Normally with NT 4.0 you have to "clone" the
NTFS system partition within the 7.8 GB limit. But not anymore...
This page will show you how you can use Windows 2000 or XP's bootsector,
ntldr and ntdetect.com to fix NT 4.0's 7.8 GB system partition limitation.
To pull this off you'll need a tool, mkbt.exe created by Bart Lagerweij.
For more information on mkbt check the mkbt page.
Mkbt.exe is used to extract or install FAT and NTFS partition boot
sector(s).
Technical
Although Windows NT 4.0 can in theory support partitions of up to 16
exabytes in size using the NTFS file system, the maximum size of the
system partition is limited to 7.8 gigabytes (GB).
What is the system partition?
The system partition is defined as the partition containing the files
needed for the initial system startup. For Windows NT, the files are
Ntdetect.com, NTLDR, Boot.ini, and sometimes Ntbootdd.sys
Why the 7.8 GB limit?
During the bootstrap process, Windows NT 4.0 uses INT13 BIOS functions
to access the drive. The INT13 functions have a maximum of 256 heads,
1024 cylinders, and 63 sectors. This is approximately 7.8 GB (512 bytes
per sector).
NOTE: Partitions other than the system partition are not affected by the
these limitations.
When trying to boot with ntldr located passed the 7.8GB limit you will
get this error message:
Os Loader V4.01
.Disk I/O error: Status = 00000001
Windows NT could not start because the following file is missing or corrupt:
\system32\ntoskrnl.exe.
Please re-install a copy of the above file.
More information about this:
Windows NT 4.0 Supports Maximum of 7.8-GB System Partition
Microsoft Knowledge Base Article - 224526
Windows NT Boot Process and Hard Disk Constraints
Microsoft Knowledge Base Article - 114841
Installation
The steps to fix NT4.0 are:
Download mkbt.exe from the mkbt page and put in on a floppy disk.
On a Windows 2000 or XP PC copy ntldr and ntdetect.com. They are
normally located in the c:\ folder and hidden. Copy them to a floppy
disk. Use mkbt.exe to extract the NTFS boot sector(s). A bootable NTFS
partition uses the first 16 sectors to store the bootstrap loader.
Use this command to extract the NTFS bootstrap loader and save it
to floppy disk:
mkbt -x -c c: a:\bootsect.bin
The -c option is for "copy" mode.
The -x option is for "expert" mode, in standard mode mkbt only
accepts floppy drives "a:" and "b:"
Goto to the "limited" NT 4.0 system, boot it and login as
administrator.
Rename the existing ntldr into ntldr.nt4
Rename the existing ntdetect.com into ntdetect.nt4
Copy the ntldr and ntdetect.com from the floppy disk on the NT 4.0
system partition, normally "c:\".
Use this command to make a backup of the current boot sector:
mkbt -x -c c: a:\bootsect.nt4
Use this command to install the NTFS bootstrap loader from floppy disk:
mkbt -x a:\bootsect.bin c:
If your NT 4.0 machine uses a fixed NT boot disk driver
ntbootdd.sys (will have "scsi" entries in your boot.ini) you must also
update that to a Windows 2000 or XP version.
Done. You can now reboot the system and see if it boot's up OK. With the
Windows 2000 or XP bootstrap loader your Windows NT 4.0 machine can have
a system partition of 2TB. This is the maximum partition value.
Remarks
THIS PROCEDURE IS PROVIDED "AS IS," WITHOUT WARRANTY OF ANY KIND,
USE AT YOUR OWN RISK!
For more information check the Nu2 license.
Don't mix languages. If you use Windows NT 4.0 English and you
install the bootsector, ntldr and ntdetect.com in Dutch language you
will get a kernel load error message.
Installing NT 4.0 Service Pack will overwrite the ntldr and
ntdetect.com! So you must update these files again!
I have tested the above on a Windows NT 4.0 machine with a 40GB
harddisk. I don't know if Microsoft supports this, so maybe you can get
into trouble whenever you talk to a Microsoft support engineer.
The second copy of the NTFS boot sector is not changed, maybe next
version of mkbt.exe will also update that. If your Windows NT 4.0
machine doesn't boot anymore because the boot files are located passed
the 7.8GB location on disk, you have 2 options:
Create a generic Windows 2000 or XP bootdisk on another machine
(see here) and boot it. Boot BartPE (Bootable CD-Rom).
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