Microsoft KB Archive/151247

= Using System.alt to Recover the System Hive =

PSS ID Number: 151247

Article Last Modified on 6/3/2003

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The information in this article applies to:


 * Microsoft Windows 2000 Server
 * Microsoft Windows 2000 Advanced Server
 * Microsoft Windows 2000 Professional
 * Microsoft Windows 2000 Datacenter Server
 * Microsoft Windows NT Workstation 3.5
 * Microsoft Windows NT Workstation 3.51
 * Microsoft Windows NT Workstation 4.0
 * Microsoft Windows NT Server 3.5
 * Microsoft Windows NT Server 3.51
 * Microsoft Windows NT Server 4.0

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This article was previously published under Q151247





SUMMARY
If your system fails to boot because the System hive is corrupt, it may be possible to rename the System.alt file to System to recover Windows. This file is located in the Systemroot\System32\Config folder.

It is recommend to first try to use the Emergency Repair Disk (ERD) to recover the System hive. Information on using the ERD can be found on page 49 in the Installation Guide. Renaming the System.alt file should only be used as a last resort after you have tried to recover the system using the ERD.

If the Windows system files are located on a Windows NT File System (NTFS) partition you will need to boot into another installation of Windows NT to rename the file. If the Windows NT files are located on a FAT partition you can boot from a bootable MS-DOS diskette to rename the file.

NOTE: In Windows 2000, you cannot manually replace a single registry hive using the Emergency Repair Disk (ERD). For additional information, click the article numbers below to view the articles in the Microsoft Knowledge Base:

229716 Description of the Windows 2000 Recovery Console

238359 Differences Between Manual and Fast Repair in Windows 2000



MORE INFORMATION
The "flush" process flushes or updates the System hive. During the flush process, changes are marked, written, and then marked as done in the System file. After this is complete the same process happens with the System.alt file. This is to ensure that during a power failure, hardware failure, or software problem you always have a good copy of the System hive.

If the System Hive becomes corrupt during this process and the information is only written to the System file but not the System.alt file, renaming the System.alt file should recover the system.

For more information on the flush process, see Chapter 23, pgs. 810 - 811 of the Windows NT Resource kit.

Additional query words: registry prodnt

Keywords: KB151247

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