The backup preference on my AG changed from "primary" to "prefer secondary" about a week ago and I'm trying to figure out why.
I created the group with a script and the script shows it was created with AUTOMATED_BACKUP_PREFERENCE = PRIMARY. I noticed about a week later that the availability databases stopped getting log backups about 2 days after I created the group. When I checked the group the backup preference was set to SECONDARY and the secondary server does not have a job set up to run log backups. I didn't change it. Is there any circumstance under which it would change on its own?
FWIW we use Ola Hallengren's backup scripts which check that setting when determining where to run the backup from.
Chuck