eG Monitoring
 

Measures reported by XChgCacheTest

The XChgCacheTest measures the performance of the Exchange 2000/2003/2007 Server Directory Service Access (DSAccess) cache. The DSAccess cache is a shared memory cache that is used by several components such as the information store, message categorizer (a component in SMTP protocol used to handle distribution list, determines the destination of the message etc), message transfer agent (MTA, used in non-SMTP delivery) or any other component or service that requires directory service information. This cache improves the performance of messaging operations like sending e-mails and provides access to both configuration information and recipient data from the Active Directory to Exchange 2000/2003/2007 Server. The idea of DSAccess cache is used to reduce the number of queries going directly to the Active Directory. This caching implementation helps to reduce the cost overhead associated with the direct access to the Active Directory.

To attain the maximum performance, the cache memory can be increased by tuning the registry key “MaxMemory” available under the tree

 “HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeDSAccess”.

The measures made by this test are as follows:

Measurement Description Measurement Unit Interpretation
Cache_hit_ratio This measure indicates the rate at which the events are being generated in the DSAccess cache.

(An event is generated whenever an object has been located in the DSAccess cache or whenever new objects have been added in the cache.)

 

 Percent A zero value for this measure may indicate that the Exchange 2000/2003/2007 Server is not performing any activity on the Active directory or no operations are happening on the Exchange 2000/2003/2007 Server itself.

A non-zero value indicates that the directory service has found the required objects in the DSAccess cache thereby reducing the access to the Active Directory.

A non-zero value for this measure also may indicate that the required objects are not found in the DSAccess cache thereby resulting in the addition of newer objects from the Active Directory.

A high value for this measure ensures better performance of the Exchange 2000/2003/2007 Server.