How to increase the kernel memory threshold

If you send or receive Microsoft Message Queuing messages, you may receive the following error: For more information, click the following article number to view the article in the Microsoft Knowledge Base:

Message Queuing stops allocating kernel memory when the kernel memory consumption exceeds 80 percent of the total available. You can send and receive messages again when the kernel memory consumption reaches less than 80 percent of the threshold.

Service pack information

To resolve this problem, obtain the latest service pack for Microsoft Windows 2000. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

Hotfix information

A supported hotfix is now available from Microsoft. However, it is intended to correct only the problem that is described in this article. Apply it only to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next Windows 2000 service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Customer Support Services to obtain the hotfix. For a complete list of Microsoft Customer Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section. This problem was first corrected in Microsoft Windows 2000 Service Pack 4.

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:

This hotfix lets you raise or lower the kernel memory threshold in Message Queuing.

In certain circumstances, you may want to raise the threshold because an application, a driver, or a system component is consuming kernel memory. Garbage collection is done by the kernel only when the paged pool memory consumption reaches 80 percent. However, Message Queuing stops functioning at 80 percent of paged pool memory consumption. If you set the kernel memory threshold above 80 percent, this makes sure that Message Queuing does not go into "low memory mode" until the Windows Memory Manager starts cleanup.

In other circumstances, you may want to lower the threshold to limit the amount of kernel memory that is used by Message Queuing.

To change the kernel memory threshold, follow these steps:

1. Install the hotfix that is mentioned in this article.
2. Add the following registry key:
   
   HKEY_LOCAL_MACHINE\Software\Microsoft\MSMQ\Parameters\KernelMemThreshold of data type DWORD
   
   The default is 80. The value can range from 1 to 99. Anything else is converted to 80.
   Note When you create this value the Decimal option must be selected. If you select Hexidecimal, the default value of 80 is used.

To change the kernel memory threshold on a clustered Message Queuing server, follow these steps:

1. Install the hotfix that is mentioned in this article on each cluster node.
2. Add the following registry key of data type DWORD on each cluster node:
   HKEY_LOCAL_MACHINE\Software\Microsoft\MSMQ\Parameters\KernelMemThreshold
3. Add the following registry key of data type DWORD on the active node in the cluster:
   HKEY_LOCAL_MACHINE\Software\Microsoft\MSMQ\Clustered QMs\MSMQ$[Clustered resource name]\Parameters\KernelMemThreshold

For more information about how to obtain a hotfix for Windows 2000 Datacenter Server, click the following article number to view the article in the Microsoft Knowledge Base: For more information about how to install multiple hotfixes with only one restart, click the following article number to view the article in the Microsoft Knowledge Base: