DOCUMENT:Q157994  09-APR-1999  [exchange]
TITLE   :XADM: Directory Store Stops While Calculating Hierarchy Table
PRODUCT :Microsoft Exchange
PROD/VER:winnt:4.0
OPER/SYS:
KEYWORDS:kbusage

======================================================================
-------------------------------------------------------------------------------
The information in this article applies to:

 - Microsoft Exchange Server, version 4.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

The Microsoft Exchange Server directory store (DS) may stop responding while
calculating the hierarchy table. Through replication, the bad hierarchy may be
copied to all other computers running Microsoft Exchange Server, causing them to
come down also.

CAUSE
=====

The DS incorrectly searches memory that was not allocated when it looks for the
non-existent parent of an orphaned entry in the hierarchy table. The search loop
looking for the parent object decrements and dereferences a pointer over and
over, eventually getting to non-allocated memory. If this hierarchy table is
replicated with orphaned objects, the problem is replicated with it.

WORKAROUND
==========

To work around this problem, obtain the hotfix mentioned below. With the hotfix,
the search loop is now checked at each iteration against the record count. If
the pointer is invalid, the object is marked as having no parent.


STATUS
======

Microsoft has confirmed this to be a problem in Microsoft Exchange Server
version 4.0. This problem was corrected in the latest Microsoft Exchange 4.0
U.S. Service Pack. 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:

======================================================================
Keywords          : kbusage 
Technology        : kbExchangeSearch kbExchange400 kbZNotKeyword2
Version           : winnt:4.0
Issue type        : kbbug
Solution Type     : kbfix

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS
PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND.  MICROSOFT DISCLAIMS
ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  IN NO
EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR
ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL,
CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF
MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.  SOME STATES DO NOT ALLOW THE EXCLUSION
OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES
SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 1999.