Increasing Windows NT Backup Performance (129999)


The information in this article applies to:

  • Microsoft Windows NT Server 3.1
  • Microsoft Windows NT Workstation 3.1
  • Microsoft Windows NT Advanced Server 3.1
  • Microsoft Windows NT Workstation 3.5
  • Microsoft Windows NT Server 3.5
This article was previously published under Q129999

SUMMARY

This article explains how you can make Windows NT Backup run faster when you back up data from universal naming convention (UNC) shares. You will notice the biggest performance gains when backing up many small files. In some tests, backup jobs that previously took three hours to complete finished in one hour.

MORE INFORMATION

To make Windows NT Backup run faster:

WARNING: Using Registry Editor incorrectly can cause serious, systemwide problems that may require you to reinstall Windows NT to correct them. Microsoft cannot guarantee that any problems resulting from the use of Registry Editor can be solved. Use this tool at your own risk.
  1. Run Registry Editor (REGEDT32.EXE).
  2. From the HKEY_LOCAL_MACHINE subtree, go to the following key:
          \System\CurrentControlSet\Services\LanmanWorkstation\networkprovider
  3. Select DeviceName:REG_SZ:\device\LanmanRedirector.
  4. From the Edit menu, choose String.
  5. Change \device\LanmanRedirector to \Device\LanmanRedirector.

    Change only the case of the first letter (d in device) -- do not change anything else.

Why This Change Makes Windows NT Backup Run Faster

Whenever Windows NT Backup encounters a file that could be a POSIX file, it requests that Windows NT open the file in a POSIX-compatible way (the path and filename match the filename case exactly).

Because the workstation service has the wrong case for the device path registry settings (the first character is lowercase), Windows NT refuses to open the file when Windows NT Backup requests POSIX semantics. As a result, Windows NT returns ERROR_FILE_NOT_FOUND. Windows NT Backup then tries to open the file without specifying POSIX semantics, which works correctly. Performance suffers because Windows NT Backup has to attempt to open a file twice.

STATUS

This design was changed in Windows NT version 3.51. The string for System\CurrentControlSet\Services\LanmanWorkstation\networkprovider is now \Device\LanmanRedirector by default.
Modification Type:MajorLast Reviewed:12/15/2003
Keywords:KB129999
©2003 Microsoft Corporation. All rights reserved.