Hi, I have a question in regards to having two Exchange 2010 SP2 servers with MBX,HUB,CAS roles installed on both servers and then using WNLB on a separate machine to load balance for fail-over.
I read from MS that:
WNLB can't be used on Exchange servers where mailbox DAGs are also being used because WNLB is incompatible with Windows failover clustering. If you're using an Exchange 2010 DAG and you want to use WNLB, you need to have the Client Access server role and the Mailbox server role running on separate servers.
I always thought that statement was true about having WNLB and Exchange server DAGs installed on the same server. But that last sentence seems to now make me believe that if the CAS role is installed on a server that uses DAG, then WNLB can't be used. Can anyone explain why this is?
I am trying to set this up so that I load balance external CAS access and internal CAS access. External will point to m.domain.com 67.xxx.xxx.xxx and internal will point to m.domain.com 172.xxx.xxx.xxx. Those two records will point to the WNLB and the WNLB will take care of the rest from there.
I was thinking this would work fine, but I had some concerns about SMTP connectivity. I was thinking that smtp would be great to have loadbalanced as well because if either server goes down, they would then still be able to connect. So I would have an mx record pointing to m.domain.com 67.xxx.xxx.xxx which points to the WNLB. The MX record would have top priority, and then I'd create a record for each HUB server with lower priority for each one. I am not concerned with the load going to one server, should it have to. I am mainly using the WNLB for CAS High Availability.
Can anyone help me with my logic?