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Q216795: Semaphore Error After Disabling Write Behind Caching

Article: Q216795
Product(s): Microsoft Windows NT
Version(s): winnt:4.0
Operating System(s): 
Keyword(s): 
Last Modified: 08-MAY-2002

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The information in this article applies to:

- Microsoft Windows NT Server version 4.0, Terminal Server Edition 
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SYMPTOMS
========

When you change the following registry subkey

  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Rdr\Parameters

  Value Name: UseWriteBehind
  Data Type:  REG_DWORD
  Data:       0

on a computer running Microsoft Terminal Server and then try to copy a file to a
remote share over the network, the following error message is displayed:

  To Many Posts Were Made to a Semaphore.

This may occur when you run the Terminal Server console and when a client is
connected to a Terminal Server Session, because both are copying files from the
Terminal Server computer to a remote share.

CAUSE
=====

This problem occurs because of a problem in the redirector, which manipulates an
operating system semaphore.


WORKAROUND

To work around this problem:

- Re-enable write behind caching by setting UseWriteBehind to 1.

-or-

- Apply the hotfix mentioned below.

RESOLUTION
==========

A supported fix is now available from Microsoft, but it is only intended to
correct the problem described in this article and should be applied only to
systems experiencing this specific problem. This fix may receive additional
testing at a later time, to further ensure product quality. Therefore, if you
are not severely affected by this problem, Microsoft recommends that you wait
for the next that contains this fix.

To resolve this problem immediately, contact Microsoft Product Support Services
to obtain the fix. For a complete list of Microsoft Product Support Services
phone numbers and information about support costs, please go to the following
address on the World Wide Web:

  http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS

NOTE: In special cases, charges that are normally incurred for support calls may
be canceled, if a Microsoft Support Professional determines that a specific
update will resolve your problem. Normal support costs will apply to additional
support questions and issues that do not qualify for the specific update in
question.

  Date       Time         Version   Size      File name   Platform
  ----------------------------------------------------------------
  02/14/99   11:10:00 PM  4.0       264,848   Rdr.sys     Intel
  02/14/99   11:09:50 PM  4.0       506,928   Rdr.sys     Alpha

  (http://support.microsoft.com/download/support/mslfiles/)

Install the latest service pack for Windows NT server 4.0, Terminal Server
Edition. Service pack 4 for Windows Terminal Server contains the fix for this
bug.

STATUS
======

Microsoft has confirmed this to be a problem in Windows NT 4.0 Terminal Server
version SP4. This problem has been corrected in the latest U.S. service pack for
Windows NT 4.0 Terminal Server version SP4. For information on obtaining the
service pack, query on the following word in the Microsoft Knowledge Base
(without the spaces):

  S E R V P A C K

Additional query words: Terminalsvr Semaphore

======================================================================
Keywords          :  
Technology        : kbWinNTsearch kbWinNT400search kbWinNTSsearch kbWinNTS400search kbNTTermServ400 kbNTTermServSearch
Version           : winnt:4.0
Issue type        : kbbug
Solution Type     : kbfix

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