I am looking at implementing a DAG across two physical sites to offer site resillience with two MB servers in one site and one (or two) in the other. My problem is I am not sure what would happen if the site to site link was to become unavilable and the servers in one site couldnt contact the witness server?
Are there any options that would allow me to specifiy another parameter to check so that the mailbox copies do not failover to the other site and become available for the users at one site? Ie can I tell the DAG to check if it can ping the other server, for example in the site before the DAG brings the databases up at the other site.
You can use high availability and site resilience to design, build, and operate a highly available messaging solution based on Microsoft Exchange Server 2010. You can design and deploy a configuration that enables site resilience, and use procedures related to the various backup, restore, and recovery operations supported by Exchange 2010.
Use the following links to access the information you need about high availability, disaster recovery, and site resilience.