Does the data-replication software perform as expected in terms of speed and data consistency?

Is there any noticeable performance impact on end users from the presence of the monitoring or data replication software?

Are the various clients able to seamlessly migrate to Exchange running on the disaster recovery server?

Deployment should be straightforward if you assembled a team of experts and successfully emulated the production environment during the testing phase. Of course, you should schedule sufficient time for the initial synchronization of the cross-site mirror and subsequent testing of fail-overs to the disaster recovery site and back to the production server. Each of those tests should validate that client redirection works as planned and that all services needed for a fully functional Exchange environment are recovered.

Following the initial deployment, it is recommended that fail-over tests be made after any change to the Exchange environment (such as installation of service packs, introduction of new services, etc.). It would be a worst-case scenario if a disaster happened at the primary location and the disaster-recovery system was unable to bring Exchange into service because of an administrative change that was not accounted for. Not surprisingly perhaps, most of the error conditions that are reported to us result from an administrator making a change within the Exchange environment and not realizing the impact on the disaster-recovery system. Even in a static environment, a test should be run at least quarterly to ensure proper monitoring and recovery.