In this section, I will review the basics for maintaining a RAC??”
including starting up a RAC and discussing how redo logs and undo tablespaces work??”and then
work through an example of an instance failure scenario using Transparent Application Failover
(TAF) as well as rebuilding a failed node and adding it back to the cluster.
Starting Up a RAC
Starting up a RAC is not much different from starting up a standalone instance; the nodes in a RAC
can start up in any order, and they can be shut down and started up at any time with minimal
impact to the rest of the cluster. During database startup, first the ASM instance starts and mounts
the shared disk groups; next, the RDBMS instance starts and joins the cluster.
On Unix, the file /etc/oratab can be modified to auto-start the instances (both the ASM instance
and the RDBMS instance) on each cluster:
# This file is used by ORACLE utilities. It is created by root.sh
# and updated by the Database Configuration Assistant when creating
# a database.
# A colon, ':', is used as the field terminator. A new line terminates
# the entry. Lines beginning with a pound sign, '#', are comments.
#
# Entries are of the form:
# $ORACLE_SID:$ORACLE_HOME:
:
#
# The first and second fields are the system identifier and home
# directory of the database respectively. The third filed indicates
Chapter 10: Real Application Clusters 383
# to the dbstart utility that the database should , "Y", or should not,
# "N", be brought up at system boot time.
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