Before you run isinteg -patch on a Microsoft Exchange Server running on a Microsoft Cluster Server you must set the environment variable _CLUSTER_NETWORK_NAME_ to the network name of the cluster. If _CLUSTER_NETWORK_NAME_ is not set, the ISINTEG utility displays the following error: "The private store could not be updated Reason: JET_errKeyDuplicate"
For example, to configure a cluster network name as EXCLUSTER, type the following at the command prompt:
SET_CLUSTER_NETWORK_NAME_=EXCLUSTER
Be sure to use the correct network name or the patch fails.