Summary

Configuration DAG(Database availability groups)

Prerequisites

1. Two Exchange Machine(Domain Joined)
2. One Witness Server

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Design

The public IP address is not displayed in the document.

Procedure

1. On the Witness Server side

1. On the Witness Server, create new folder in the "C:\"
   
2. Share the Witness folder
   
3. Click find people
   
4. Add 'Exchange Trusted Subsystem
   
5. And assign the permission level as Read/Write
   
6. Done
   
7. Add 'Exchange Trusted Subsystem' to the local administrator group.
   Use 'compmgmt.msc' in the 'run'
   

2. On the ECP side

1. Configure database availability groups

1. Create DAG
   

2. Add membership
   

3. Add the exchange servers
   

4. Click save
   

5. All member servers are added to the DAG
   

2. Configure databases servers with copies

1. Go databases
   
2. Click 'more(three dots)' and 'Add database copy'
   
3. Browse and select the second Exchange server and save
   
4. After do the same work to the each of the Exchange server, the configuration of the DAG is done
   

Reference

https://learn.microsoft.com/en-us/exchange/high-availability/database-availability-groups/database-availability-groups?view=exchserver-2019