Creating an Emergency Repair Disk

When you install Windows NT, Setup creates the Registry information in %systemroot%\System32\Config. For recovery purposes, Setup also creates a %systemroot%\Repair folder that contains the following files:

File Name	Contents

Autoexec.nt	Copy of %systemroot%\System32\Autoexec.nt, which is used to initialize the MS-DOS environment.
Config.nt	Copy of %systemroot%\System32\Config.nt, which is used to initialize the MS-DOS environment.
Default._	Registry key HKEY_USERS\DEFAULT, compressed.
Ntuser.DA_	Compressed version of %systemroot%\Profiles\Default User\Ntuser.dat. The repair process uses Ntuser.da_ if this one needs to be repaired.
Sam._	Registry key HKEY_LOCAL_MACHINE\SAM, compressed.
Security._	Registry key HKEY_LOCAL_MACHINE\SECURITY, compressed.
Setup.log	Log of which files were installed, and cyclic redundancy check (CRC) information for use during the repair process. This file is Read Only, System, and Hidden, so it will not be visible unless you have configured My Computer or Windows NT Explorer to show all files.
Software._	Registry key HKEY_LOCAL_MACHINE\SOFTWARE, compressed.
System._	Registry key HKEY_LOCAL_MACHINE\SYSTEM, compressed.

During installation, Windows NT Setup asks whether you want to create an Emergency Repair Disk. You should choose Yes. When you create an Emergency Repair Disk during installation, or later by using the Repair Disk program (Rdisk.exe), the files are copied from %systemroot%\Repair to the floppy disk. You can also use the Emergency Repair Disk to repair a corrupt Partition Boot Sector for the system partition.

When you run the Repair Disk program, you can update the %systemroot%\Repair\Software and %systemroot%\Repair\System files with the current information in %systemroot%\System32\Config by using the Update Repair Info button.

The Repair Disk program does not update the Default, Sam and Security files if you run the program from Windows NT Explorer or My Computer. To update all the files, you can run rdisk from the command prompt by entering:

rdisk /s

You can also update all of the files by clicking the Start button, clicking Run, and entering:

rdisk /s

Using the /s switch forces the Repair Disk program to update all of the Registry keys in the %systemroot%\Repair folder.

There are several points to consider about maintaining and using your Emergency Repair Disk:

If you did not use the /s switch before you create the Emergency Repair Disk, and you use the Repair process to replace the SYSTEM Registry keys, all passwords in the system return to the passwords in effect at the time you last updated the Sam and Security files in %systemroot%\Repair. If you have more recently backed up these keys by using Windows NT Backup, Regback.exe, or Regedt32.exe, you can restore more current information.
If you did not update the Emergency Repair Disk after using Disk Administrator to configure volume sets, stripe sets, mirror sets, or stripe sets with parity, it might be difficult or impossible to recover data on these volumes. When you create any of these volumes, Disk Administrator updates the DISK subkey in the Registry and sets the fault-tolerant bit on the System ID field of the Partition Table for each partition or logical drive in the volume.
You should make a copy of your current Emergency Repair Disk.
If you convert your boot partition from the FAT file system to the NTFS file system on an x86-based computer, be sure to update your Emergency Repair Disk. The NTFS Partition Boot Sector must be on the Emergency Repair Disk, not the FAT Partition Boot Sector.
The Emergency Repair Disk is not a replacement for backups.

For more information about creating an Emergency Repair Disk, see Help for the Repair Disk program. For more information about the %systemroot%\Repair and %systemroot%\System32\Config folders, and the Emergency Repair Disk, search the Knowledge Base. For information about the Knowledge Base, see Chapter 8, "General Troubleshooting."

Chapter 23, "Overview of the Windows NT Registry," in the Windows NT Workstation Resource Guide, contains more information about these keys and the %systemroot%\System32\Config folder.