In vSphere 4.1, several properties and types have been deprecated. The following table from vSphere Web Services SDK 4.1 release note lists each deprecated API element and its replacement.
Name of deprecated type, method, or property As of vSphere API 4.1, use instead… Methods
Data Object Properties
PerformanceManager memory overhead counter
Note that the release note has much more information that you should really read through if you use vSphere 4.1 API.
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