How to Remove the MPHeap Parallelism Registry Value

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In Exchange 2000, each time the Microsoft Exchange Information Store service is started, the Exchange store process (Store.exe) gets its initial process-heap. Then, a module loaded in the information store process—ESE.DLL—allocates 4 JET heaps for each processor present in the system.

Note

Although these heaps are separate pools of memory in the information store process, they are collectively referred to as the ESE multi-heap.

On a single CPU system, ESE allocates 4 JET heaps. On a dual CPU system it allocates 8; on a quad system it allocates 16; and so forth. When Exchange 2000 was installed on systems with four or more CPUs, it was found that the ESE multi-heap caused excessive virtual memory consumption, which in turn led to performance problems. To correct this problem, it was recommended that customers with large Exchange 2000 servers add the MPHeaps parallelism registry value to their systems. Exchange 2003 now automatically calculates the optimum number of heaps to allocate based on the unique specifications of each system. Therefore, the MPHeaps parallelism registry value should be removed from Exchange 2000 servers after Exchange Server 2003 is installed.

Before You Begin

Before you perform the procedure in this topic, be aware that the procedure contains information about editing the registry.

Warning

Incorrectly editing the registry can cause serious problems that may require you to reinstall your operating system. Problems resulting from editing the registry incorrectly may not be able to be resolved. Before editing the registry, back up any valuable data.

Procedure

To remove the MPHeap parallelism registry value

  1. Start Registry Editor.

  2. Navigate to HKLM\Software\Microsoft\ESE\Global\OS\Memory

  3. In the right pane, delete the MPHeaps parallelism registry value.

  4. Close the registry editor and restart the Microsoft Exchange Information Store service for the change to take effect.

For More Information

For information about how to edit the registry, see Microsoft Knowledge Base article 256986, "Description of the Microsoft Windows Registry," (https://go.microsoft.com/fwlink/?linkid=3052&kbid=256986).