Hi there guys.
I have 2x Exchange 2013 CU1 in DAG that needs upgrading to CU5. As I do not want to cause any downtime, I wanted to first upgrade one of the servers & test for a few days before upgrading the other server. Question is, will the DAG & all other services still work OK if one server is on CU1 and the other on CU5?
Should I first upgrade the passive member in failover or the active? Can you help me with a roadmap?
Lastly, I also need to upgrade the operating system from Server 2012 to Server 2012 R2 - should I do this before or after upgrading Exchange and why?
Here's my configuration scope:
CONTOSO1 - Server 2012 - Exchange 2013 CU1 - Primary Exchange Server - MB & CAS Roles - Active member in Failover Cluster
CONTOSO2 - Server 2012 - Exchange 2013 CU1 - Secondary Exchange Server - MB & CAS Roles - Passive member in Failover Cluster
CONTOSO3 - Server 2012 - DAG Witness Server