Exchange High Availability and Site Resilience
I have a Multi-Tenant Exchange organisation with customers added using Control Panel software
The site consists of two Exchange 2013 servers and all servers are physical machines. I was unable to create a DAG as when the OS’s were installed server A was installed with 2012 standard and Server B was installed with 2012R2 standard. When we add new customers using the Control Panel everything is fine and mailboxes get created on one or other of the two Exchange servers which I have read in various articles is usual practice unless otherwise configured not to.
This situation is not satisfactory as I cannot create I cannot create a DAG for high availability which was the original intention.
Therefore, I have created two more Exchange 2016 servers in the organisation with Server 2012R2 Standard OS on each one – so server C and server D now have Exchange 2016 and I have created a DAG with Servers C and D as members and added DBC01 and DBD01 databases to the DAG.
My aim is to move all mailboxes from server A and B databases to server C (DBC01) so they are replicated to database DBD01 on server D and then to de-commission server’s A and B from the organisation.
So for now I have four exchange servers each with externally facing AD and different URL’s for example...
https://exchange-a.mydomain.com - https://exchange-b.mydomain.com - https://exchange-c.mydomain.com - https://exchange-d.mydomain.com
I have migrated a few mailboxes already to server C and Outlook clients have detected the change in the server name to connect to but it has not been entirely without problems, some users say that email doesn’t leave the outbox unless they restart Outlook and not all new emails are showing as quickly as they should. I have also noticed that some Outlook clients are connection to server D instead of server C where the migrated mailboxes reside.
My question is this. Have I not done something I should have for example created a Namespace rather than have individual server URL’s something like Office 365 which uses https://outlook.office365.com
All servers have a send connector configured to send to a smart host relay server and all receive connectors are configured out of the box I am led to believe.
When server’s A and B are gone we will be introducing another two exchange servers on our second site for site resilience. So I am thinking of an Unbound namespace.
Can someone tell me how my Exchange server external URL’s should be configured and how to do it should they all be the same on each server with a common namespace?
Late note: I have just had this feedback from a customer I have migrated to server C Exchange 2016 - "Emails stored in ‘Outbox’ but not sent. I have to close Outlook and reopen it to clear the problem"