Hi, I have two Data Centers, each with active users so I created the following DAG configuration: DAG1 - Two Mailbox servers in Site1 and one Mailbox server in Site2 DAG2 - Two Mailbox servers in Site 2 and on Mailbox server in Site1 This way users in Site1 will use DAG1 and users in Site2 will use DAG2. Because we have a majority of DAG members at each site we can suffer a WAN outage and users at each site still are online. I have read this posting and think I understand but wanted your opinion Purpose of File Share Witness in Odd number member DAG Exchange 2010 Questions: Q1) Since I have an odd number of members in my DAG I do not need to configure a Witness server or Alternate Witness server in the DAG property ? Q2) Exchange automatically created a Witness server entry when I created my DAGs as it didn't know whether I was going to end up with an even or odd number. Should I delete the Witness server entry and Alternate Witness server entry so both are blank? Q3) Is there any reason why I would use FSW on a DAG with odd members ? Q4) This article ( http://technet.microsoft.com/en-us/library/dd298065.aspx ) says: As a best practice, in an environment where a DAG is extended across multiple datacenters (and Active Directory sites) and configured for site resilience, we recommend that you use a witness server in your primary data center (the data center containing the majority of your user population). Why should I do this if I have DAGs with odd number ? Many thanks for your input

Technically there does not need to be an FSW when you have an odd number of mailbox servers in a DAG, but I would create one anyway just in case you choose to add or remove a DAG member at some point in the future. The FSW is not a voting member. The DAG consults it only when there is a tie vote among the voting members, which are mailbox servers. Therefore, if you have an odd number of nodes, the FSW will not be consulted whether or not it is present. Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."