active_instance_count behavior

  • From: John D Parker <orclwzrd@xxxxxxxxx>
  • To: oracle-l <oracle-l@xxxxxxxxxxxxx>
  • Date: Tue, 14 Nov 2006 12:22:08 -0800 (PST)

Ok, in a 2 node RAC, 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.

Other related posts: