DOCUMENT:Q194351 10-AUG-2001 [winnt] TITLE :Read Errors After Primary Member of Mirror Set Fails PRODUCT :Microsoft Windows NT PROD/VER:winnt:4.0 OPER/SYS: KEYWORDS:kbWinNT400sp4fix ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft Windows NT Server version 4.0 - Microsoft Windows NT Server version 4.0, Terminal Server Edition ------------------------------------------------------------------------------- SYMPTOMS ======== If the system experiences a failure on a mirror set, Windows NT will break the mirror and orphan the faulty drive. There may be a situation where bad data is passed back to applications after breaking the mirror. This can cause a variety of problems, such as application problems and read media errors on a healthy disk. In addition to symptoms: - A server with hot pluggable disk system (for example: Compaq, HP) - Mirror set created in the disk system When you unplug the mirror disk while online from the mirror set (for example, hardware failure), a warning message is received that the mirror set is broke. The server and the original disk are functioning correctly. After you shut down the server, replace the mirror disk and then restart the system, you may encounter file corruption with the original disk. Disk Administrator may report a healthy status for the mirror set. CAUSE ===== Although one of the mirrored disks was orphaned because of hardware failure, users continue to use the system without replacing the failed disk and re-creating the mirror set. During this time, disk I/O is suppose to be performed only from the partition of the healthy disk. If an application requests data from the disk, and a read I/O error is encountered on the healthy disk, Ftdisk.sys erroneously retrieves data from the orphaned disk, which results in unreliable data from the orphaned disk being returned to the application as reliable data. RESOLUTION ========== To resolve this problem, obtain the latest service pack for Windows NT 4.0 or Windows NT Server 4.0, Terminal Server Edition. For additional information, please see the following article in the Microsoft Knowledge Base: Q152734 How to Obtain the Latest Windows NT 4.0 Service Pack -or- To work around the problem, before you shut down the server and replace the disk, you should manually break the mirror set in Disk Administrator. For additional information, please see the following article in the Microsoft Knowledge Base: Q120227 Steps to Recover a Failed Mirrored System/Boot Partition STATUS ====== Microsoft has confirmed this to be a problem in Windows NT 4.0 and Windows NT Server 4.0, Terminal Server Edition. This problem was first corrected in Windows NT 4.0 Service Pack 4.0 and Windows NT Server 4.0, Terminal Server Edition Service Pack 4. Additional query words: scsi dirty mirroring ====================================================================== Keywords : kbWinNT400sp4fix Technology : kbWinNTsearch kbWinNT400search kbWinNTSsearch kbWinNTS400search kbWinNTS400 kbNTTermServ400 kbNTTermServSearch Version : winnt:4.0 Hardware : ALPHA x86 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 2001.