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Oracle Tips by Burleson |
Oracle10g Grid Computing
with RAC
Chapter 13 - Oracle RAC Backup and Recovery
Recovery
in the RAC Environment
As noted
earlier, there are basically two types of failure in a RAC
environment, instance and media. Instance failure involves the loss of
one or more RAC instances, whether due to node failure or connectivity
failure. Media failure involves the loss of one or more of the disk
assets used to store the database files themselves.
If a RAC
database undergoes instance failure, the first node still available
that detects the failed instance or instances will perform instance
recovery on all failed instances using the failed instances redo logs
and the SMON process of
the surviving instance. The redo logs for all RAC instances are
located either on an OCFS shared disk asset or on a RAW filesystem
that is visible to all the other RAC instances. This allows any other
node to recover for a failed RAC node in the event of instance
failure.
Recovery
using redo logs allows committed transactions to be completed.
Non-committed transactions are rolled back and their resources
released.
An instance
failure resulting in a non-recoverable situation with an Oracle
database is rare. Generally speaking, an instance failure, in RAC or
in normal Oracle, requires no active participation from the DBA, other
than to restart the failed instance when the node becomes available
once again.
For more information,
see the book
Oracle 11g Grid and Real Application Clusters - 30% off if
you buy it directly from Rampant TechPress .
Written by top
Oracle experts, this RAC book has a complete online code depot with
ready to use RAC scripts.
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