Ok, in a 2 node RAC 18.104.22.168(yes, I know, don't ask). We have an active/passive configuration with active_instance_count=1 set in both instances. This makes instance prd1 the primary. My question hinges around behavior of block mastering and cache coherency. In normal active/active RAC, each node "masters" approx half the datablocks. Does this behavior change when I have a primary node? I would think i would. However, I can't find any docs one way or the other. With a Primary node and blocks being mastered like in active/active, the primary node would be continually asking the passive node for blocks which seems very inefficient. It would make more sense for the primary node to master all the blocks and behave much like a pre 8.1.7 OPS node. Any thoughts here? I'd really like to see some docs one way or the other but I can't seem to locate any. John Parker --------------------------------- Cheap Talk? Check out Yahoo! Messenger's low PC-to-Phone call rates.