Performance Monitor shows Log Stalls/sec are regularly greater than zero in Exchange Server 5.5

Microsoft Exchange Server 5.5 frequently sets the Log Record Stalls/sec buffer value too low (less than 80 buffers) for large computers. We recommend that a significantly larger number of buffers, like 256 or 512, be used.

Log stalls can have a significant effect on performance. Each log stall causes a call Sleep ( 1 ). This continues to be called until the log operation does not return the stall error.

Note Microsoft Exchange 2000 Server and Microsoft Exchange Server 2003 store the log buffer value in the Active Directory directory service. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

When you monitor the Performance Monitor counter, "Database - Log Record Stalls/sec," you may notice that the value is regularly greater than zero on large computers that are under heavy load.

The Performance Monitor describes this counter as: "Log Record Stalls/sec is the number of log records that cannot be added to the log buffers per second because they are full. If this counter is non- zero most of the time, the log buffer size may be a bottleneck."

Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.

For information about how to edit the registry, view the "Changing Keys And Values" Help topic in Registry Editor (Regedit.exe) or the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe. Note that you should back up the registry before you edit it. If you are running Microsoft Windows NT, you should also update your Emergency Repair Disk (ERD).

You can reduce Log Record Stalls/sec by increasing the number of log buffers that are available to Microsoft Exchange. To do this, you must add the following registry parameter:

1. Start Registry Editor (Regedt32.exe).
2. Locate the following key in the registry:

       HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
       \MSExchangeIS\ParametersSystem
   						

   Note The previous registry key is one path. It has been wrapped for readability.
3. On the Edit menu, click Add Value, and then add the following registry value:
   Value Name: Log Buffers
   Data Type: REG_DWORD
   Value: > 80 decimal
4. Quit Registry Editor.

Each buffer holds one log sector. Each log sector is equal to the sector size of your log disk (almost always 512 bytes).