How do I dictate the order of preferred replica on a Always On cluster? I have a problem, I look after a massive estate. the newer AO clusters I built myself and they work fine. I have inherited once AO cluster which is often problematic. However, migrating isn't an option ATM.
My current problem is I notice Netbackup wouldn't take backups from the secondary. After investigation, I found it was trying to take the backup from the DR instance. I've set it to take from the Primary for now.
Current behaviour
AUTOMATED_BACKUP_PREFERENCE = PRIMARY

preferred replica results
DR = 0
primary = 1
secondary = 0
AUTOMATED_BACKUP_PREFERENCE = SECONDARY_ONLY

preferred replica results
DR = 1
primary =  0
secondary = 0
The behaviour I need it to be is how can I get it to be,
AUTOMATED_BACKUP_PREFERENCE = SECONDARY_ONLY

preferred replica results
DR = 0
primary =  0
secondary = 1
However I can't find anything on Microsoft to point me in the right direct?
You can set the backup Priority to be higher on your non-DR node

By curiosity, why are you taking backup on the secondaries ?
There is some cases where your secondary could be out of sync with the primary (even if you set you AG to by Sync), for that reason, I usually prefer to have my backup done on my primary node.
Also, if you take the backup on the secondary node, are you also running checkdb on that secondary node ? (you don't want to end up doing backup of a corrupted secondary)