Add a metadata controller to an Xsan in macOS Server
You add additional standby metadata controllers to the SAN for data integrity, controller redundancy, and improved performance.
Each additional controller automatically gets its SAN configuration information from the master controller when it’s set up, and it also becomes an Open Directory replica.
Connect a new computer to the SAN networks (Fibre Channel and Ethernet).
Open Server on the new computer, then go through initial Server setup.
In the Server app sidebar, select Xsan from the list of advanced services.
Turn on the service.
The Xsan setup assistant appears.
Choose “Join an existing SAN as a controller,” then click Next.
Select the existing SAN from the list, then click Join.
If you don’t see the SAN, choose Other and enter the first controller’s IP address, administrator name and password, then click Connect.
Enter an administrator name and password, then click Join.
Click Join to finish the assistant.
Verify the additional controller by selecting the Controllers tab and inspecting the list.
In the list, you should see all the controllers, including the current computer.
After you add a controller to the SAN, volumes that are mounted on all other controllers are mounted automatically on the new controllers.