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The Oracle integration uses a VIP as a client to guarantee failover.
Figure 11. Oracle Integration configuration windows
Node Affinity awareness: In a RAC environment, some nodes of the cluster have faster access to
specific datafiles. RMAN is aware of the node affinity, and will try to assign specific datafiles to the
channels of the nodes which have faster access to these datafiles.
In the Appendix C, you can find two session reports using this configuration:
• Backup using service BACKUP (Session 3)
• Backup using service MSL5000 (Session 4)
Use a VIP and allocate the channels to the instances manually
In the above examples, when we define a Service with Load Balancing (for instance BACKUP and
MSL5000), we let Oracle take the decision about the number of channels which will be started per
configured instance. As it can be seen in some session reports, it could happen that channel
distribution is not optimal for the backup (that is, only two of the four instances have channels or one
instance gets three out of four channels).
To overcome this situation, channels can also be allocated to specific instances manually. In this case,
it is recommended that one channel is allocated per drive device. The optimal situation is to have the
same number of drives as instances, thus allocating one channel per instance (each node has a
dedicated drive). This approach has a downside: if one of the instances is not available at backup
time, the backup session will fail (the channel cannot be allocated on that node).
In our environment, we allocate two channels, one on RAC1 and one on RAC2, writing to two tape
drives. To allocate channels manually, we need to edit the RMAN script in the GUI. For this purpose,
create a new backup specification; choose the drives for the backup with the right number of
channels (tape concurrency), save it and then edit the RMAN script by adding the connection string at
the end of the channel specification.
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