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Exchange 2010 Stretch Cluster – 3 (One DAG vs Multiple DAG)

Posted by Brajesh Panda on May 12, 2010

This is a obvious question always asked by my customers; Do we need single DAG or Multiple DAG?

Answer differs as per the requirement –

1. If all mailbox servers are located in same site, there is no good justification having multiple DAGs; this is going to limit number of members; hence copies too. Because each Mailbox server can be part of one DAG.

2. Let suppose customer is stretching the DAG between sites for site level redundancy;  Number of DAGs depends on how  many sites going to host active mailbox databases.  If  both sites or multiple sites going to have active databases we are going to need multiple DAGs stretching across sites. Because if you consider one DAG with multiple active databases in different sites, WAN failure is going to bring down those remote site databases which don’t have Quorum. So better to have multiple DAG with quorum in each site.

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