In RAC, a Database Instance on a node requires a VIP to also be running on that node, otherwise the Instance will not start. This is known in the 11gR2 RAC Admin Guide as strong start dependency.
However I now believe that with Server Pools and Policy Managed Databases introduced in 11gR2, there is now weak start dependency i.e. that the RAC Instance on a node can start even if the VIP is not started on that same node.
Q1. Is this because the VIP could be running on another node in the Server Pool for the VIP ?
Q2. So the VIP could be assigned to a Server Pool that has different nodes than the Server Pool assigned to the RAC Database - is that correct ?
Q3. I presume it is not saying that the RAC Instance does not need a VIP before starting, rather what it is saying, is that the required VIP for that Instance may not necessarily be running on the same node as that Instance ?
Trying to get my head around that ! As in the past the only reason a VIP wouldn’t be running on the intended node, would be if the node failed and the VIP had been inherited by another node. In that case there were be 2 VIPs on the same node being serviced by the same Instance.
Q4. Now what we appear to be saying is that a VIP and associated Instance could be on separate nodes – is that correct ?
any advice greatly appreciated,
thanks Jim