How to Generate a Memory Dump File When a Server Stops Responding (Hangs)

If a Windows NT 4.0-based or a Windows 2000-based server stops responding (hangs), you can create a memory dump file to troubleshoot the issue. When you create a memory dump file, it is similar to forcing a bug check or a Stop error on the server.

To perform the procedure that is described in this article, you must have second computer called Remote Debugger and a NULL modem cable.

NOTE: If you use Windows 2000, you can transfer the memory from the console. If you use this functionality, you do not have to use a Remote Debugger computer; however, Windows may not create a dump file for the computer each time it stops responding.

For additional information about how to create a memory dump file on a Windows 2000-based computer, click the article number below to view the article in the Microsoft Knowledge Base:

Procedure on the Server

Important Use one of the following procedures to prepare the server before the server hangs the next time.

Windows NT 4.0

Perform the following procedure on a Windows NT 4.0-based server that is not responding:

1. Right-click My Computer, and then click Properties.
2. Click the Startup/Shutdown tab.
3. Make sure that the Write Debugging Information check box is selected and that the file location is valid.
4. Attach the NULL modem cable to the server's serial port.
   
   NOTE: For the rest of these instructions, use the COM1 port; however, you also can use the COM2 port.
5. Edit the Boot.ini file. To do so:
   1. Copy the typical boot up entry, and then append it to the end of the Boot.ini file.
   2. Add the following line, and then mark the description as a DEBUG boot:
      /debug /debugport=com1 /baudrate=57600
      The Boot.ini file will look similar to the following text:
      [boot loader]
      timeout=30
      default=multi(0)disk(0)rdisk(0)partition(1)\WINNT
      [operating systems]
      multi(0)disk(0)rdisk(0)partition(1)\WINNT="Windows NT Server Version 4.00"
      multi(0)disk(0)rdisk(0)partition(1)\WINNT="Windows NT Server Version 4.00 [VGA mode]" /basevideo /sos
      multi(0)disk(0)rdisk(0)partition(1)\WINNT="Windows NT Server Version 4.00 Debug" /debug /debugport=com1 /baudrate=57600
6. Restart the server, and then click Debug boot.

Windows 2000

Perform the following procedure on a Windows 2000-based server that is not responding:

1. Right-click My Computer, and then click Properties.
2. Click the Advanced tab, and then click Startup and Recovery.
3. Click Complete Memory Dump, and then make sure the dump file memory location is valid.
4. Attach the NULL modem cable to the server's serial port.
   
   NOTE: For the rest of these instructions, use the COM1 port; however, you also can use the COM2 port.
5. Edit the Boot.ini file. To do so:
   1. Copy the typical boot up entry, and then append it to the end of the Boot.ini file.
   2. Add the following line, and then mark the description as a DEBUG boot:
      /debug /debugport=com1 /baudrate=57600
      The Boot.ini file will look similar to the following text:
      [boot loader] timeout=30 default=multi(0)disk(0)rdisk(0)partition(1)\WINNT [operating systems] multi(0)disk(0)rdisk(0)partition(1)\WINNT="Microsoft Windows 2000 Advanced Server" /fastdetect multi(0)disk(0)rdisk(0)partition(1)\WINNT="Microsoft Windows 2000 Advanced Server" /fastdetect /debug /debugport=com1 /baudrate=57600
6. Restart the server, and then click Debug boot.

Procedure on the Remote Debugger Computer

Windows NT 4.0 and Windows 2000

1. Attach the other end of the NULL modem cable to the Remote Debugger computer on its COM1 port.
2. Install the Debugging tools from the Windows CD.
   
   The debugging tools are located in the Support\Tools folder on the Windows 2000 CD and in the Support\Debug\I386 folder on the Windows NT 4.0 CD. You can also install the Debugging tools from the Web. To do so, visit the following Microsoft Web site:
   http://www.microsoft.com/whdc/default.mspx (http://www.microsoft.com/whdc/default.mspx)
3. Run WinDBG.
4. On the File menu, click Kernel Debug.
5. Set the baud rate to 57600, set the COM port to 1, click OK, and then click No to save the workspace.
6. On the Debug menu, click Break.
7. After you receive the message that states that you have pressed CTRL+BREAK, type .crash.
8. On the File menu, click Exit, and then click No to save the workspace.
9. After the dump file is created, use Dumpchk.exe from the Debugging tools to verify the integrity of the dump file.
10. Send the dump file to a Microsoft Support Professional for analysis.

You may have to reduce the physical memory of the server to produce a valid dump file. When you initiate the dump file creation procedure, the contents of the physical RAM are written to the paging file that is located on the partition on which the operating system is installed. When you restart the computer, the contents of that paging file are written to the dump file. Physical RAM cannot be more than 2 gigabytes (GB) for a complete memory dump file creation procedure. Additionally, the page file on the partition on which the operating system is installed must be at least the size of the physical RAM plus 50 megabytes (MB). If you reach the 2-GB limit or if disk space issues occur on the partition on which the operating system is installed, you may have to reduce the physical RAM of the server. To do so, use the maxmem switch in the Boot.ini file.

For additional information about the MAXMEM switch, click the article number below to view the article in the Microsoft Knowledge Base: Note If your server has a feature such as the Automatic System Restart (ASR) feature in Compaq computers, disable it. It can interrupt the dump process. On Compaq systems, ASR can be disabled in the BIOS. The third-party products that are discussed in this article are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, regarding the performance or reliability of these products.

For additional information, click the article numbers below to view the articles in the Microsoft Knowledge Base: