Question: Why do
we need master node in Oracle RAC ? What are the
architectural difference between the master node and the
other nodes in RAC?
able to keep track of the resources in a RAC cluster. There
is no true concept of a master node in Oracle RAC. Instead,
each instance in the cluster becomes the resource master for
a subset of resources. See
these notes on RAC.
Instead, the RAC master node has the
smallest node ID in the RAC cluster, and is usually the
first node started in the cluster. . Node-ids are
assigned to the nodes in the same order as the nodes join
the cluster. Hence, normally the node which joins the
cluster first is the master node. However, in cases
In case of
node eviction, the RAC cluster is divided into two
sub-clusters, each with it's own master node.
The sub-cluster containing fewer no. of nodes is evicted.
But, in case both the sub-clusters have same no. of nodes,
the sub-cluster having the master node survives whereas the
other sub-cluster is evicted.
You can run these OS queries to see the RAC master node:
$ORA_CRS_HOME/log/`hostname`/cssd/ocssd* |grep master
x in `ls -tr $ORA_CRS_HOME/log/`hostname`/cssd/ocssd* `; do
grep -i "master node" $x ; done | tail -1
Oracle Training from Don Burleson
The best on site
training classes" are just a phone call away! You can get personalized Oracle training by Donald Burleson, right at your shop!
Burleson is the American Team
documentation was created as a support and Oracle training reference for use by our
DBA performance tuning consulting professionals.
Feel free to ask questions on our
considering using the services of an Oracle support expert should
independently investigate their credentials and experience, and not rely on
advertisements and self-proclaimed expertise. All legitimate Oracle experts
Oracle technology is changing and we
strive to update our BC Oracle support information. If you find an error
or have a suggestion for improving our content, we would appreciate your
and include the URL for the page.
Copyright © 1996 - 2017
All rights reserved by
is the registered trademark of Oracle Corporation.
Remote Emergency Support provided by