Oracle CRS 10.2.0.3 patchset brings long awaited removal of previously required dependencies of databases and ASM instances on a VIP. Actually, 10.2.0.2 patchset lifted the requirement for dependency between ASM instance and VIP but not for database instances. In 10.2.0.2 this dependency wasn’t removed by default.
For those who don’t know that – in case public interface(s) fail(s) (or whatever the case when VIP failure detected) and VIP relocated to another node, CRS shutdowns ASM instance and ALL database instance on the node with failed VIP. When I was working for another good company, we had a lengthy argument with Oracle about supported way of removal for this dependency – there is a way to remove it manually but this wasn’t supported and, particularly, FAN (Fast Application Notification) functionality was not guarantied to work properly in this case.
There are several reasons why one wouldn’t want to have database and ASM instances to be dependent on the VIP.
There might be more than single interface used to connect to the database instances by different applications. VIP failover followed by shutdown of all database instances would terminate all services even though they might still be available over other interfaces. Large data-centers often have dedicated networks for certain types of traffic and/or different applications.
It takes time to start ASM and database instances back when VIP is returned to its original node. Recovery from network failure would take only few seconds without shutting ASM and database instances down.
Non-RAC database hosted on the same cluster
You wouldn’t want to use VIP to connect to a non-RAC database anyway and wouldn’t want this database to go down on VIP failure.
I hope Oracle will come up with multiple VIPs at some point so that we don’t need to poke around with user VIPs to use multiple interfaces.