We are looking to run Exchange 2003 on a virtual server, but host the data files on a Windows Storage Server NAS device. We’d like to implement a failover mechanism. Whereas we are likely to use (or at least investigate) Microsoft’s DFS file replication system for mirroring standard files, it isn’t recommended for database applications. There do appear to be third-party solutions, such as HP’s StorageWorks mirroring software, but that’s expensive. Does anyone have any recommendations?