HP StorageWorks Cluster Extension is used

[alainyaza]

hi experts, i am really confused about for what HP StorageWorks Cluster Extension is used?

because for example if we are talking about exchange 2010 with 2 sites and 2 eva 8400 i will talk only about mailbox servers site1: 2 exchange mailbox servers and 1 eva 8400 presented to this mailbox servers where the database and the logs are saved

site 2: 2exchange mailbox servers and 1 eva 8400 presented to this mailbox servers where the database and the logs are saved

so to provide disaster recovery we can put all the 4 mailbox servers in the same DAG which will provide the replication of the database and the failover between the 2 sites.

so please can somebody explain for me for what to use HP StorageWorks Cluster Extension is used as the failover between 2 sites can be provided by application level clustering?  in our case even if the storage fails and the database is not anymore presented to the mailbox server it will be considered as a failure and the exchange mailbox server will fail over to another server in the dag