in exchange 2010 you have DAG HA (=automatic failover) and Site resilency (=manual failover & equal to disaster recovery mode). If there are 2 datacenters with 1 AD site (stretched) HA automatic failover is supported. If there are 2 AD sites across 2 datacenters, the recommended solution should be "site resilence" mode. => Is this correct? Because following MS engineer this is supported, but I'm doubting. (I read a lot articles and forums, but is not very clear)
If in DAG there are 3 members, 2 in DC1 site & 1 in DC2, [formular =>(N/2)+1= ?)], do I need a FSW? (Normally not). And also in "majoirty node" in this scenario can I still create a FSW in DC1 and an alternate FSW in DC2 and enable DAC for 1 AD site with HA without "site resilence" in case the 2 servers in DC1 goes down or network connection between the 2 Datacenters are broken?
Or ideal solution would be in DC1 2 mbx servers and in DC2 1 mbx server in same DAG; the 2 servers in DC1 in HA and server in DC2 using as DR (=site resilence); 1 FSW in DC1 and in DC2 an "Alternate FSW" and also DAC enabled. Is this correct?