Today I took a look at a clients 10g Oracle RAC environment where one node apparently had started misbehaving quite some time ago. The scenario was that both nodes were up, cluster ready services was up, nodeapps were up, ASM was up but the instance was down. Starting from the top with the database alert log, it was apparent that ASM had no available disk groups for this database. Okay, let’s ask ASM what it feels, then. Looking in the ASM log file it was equally obvious that the ASM instance was online but didn’t service any disk groups. That’s odd.