RAC cluster configuration is designed so that in the event
of a node failure, another node with a separate instance of Oracle
can continue processing transactions. Figure 1-3 “Before
Node Failure” shows a typical cluster with instances running
on both nodes.
Figure 1-4 “After
Node Failure” shows the condition
where Node 1 has failed and Package 1 has been transferred to Node
2. Oracle instance 1 is no longer operating, but it does not fail
over to Node 2. Package 1’s IP address was transferred
to Node 2 along with the package. Package 1 continues to be available
and is now running on Node 2. Also note that Node 2 can now access
both Package 1’s disk and Package 2’s disk. Oracle
instance 2 now handles all database access, since instance 1 has
gone down.
In the above figure, pkg1 and pkg2 are not instance packages.
They are shown to illustrate the movement of packages in general.