Database Reference
In-Depth Information
Candidate servers
:
Lists the names of all candidate nodes that are eligible for instance
failover operations. In the event of instance failure, it is important to know that Oracle
will select a server randomly, in no particular order, to fail over the instance. Hence, it is
strongly recommended to use SCAN to connect to the database to avoid any connection
failures on instance migration or failover over different nodes.
Verifying the Online Relocation Status
Execute the following command to verify the database's online relocation status:
# srvctl status database -d RONDB
Instance RONDB_1 is running on node rac1
Online relocation: INACTIVE
This output illustrates that the RONDB_1 instance is currently active on node rac1. More importantly, no online
database relocation is taking place at this moment.
Stop and Start the Database
Like that of other typical RAC and non-RAC databases, a RAC One Node database's shutdown/startup can be
performed either from the SQL*Plus prompt or using the srvctl utility. Though the srvctl usage is highly recommended
for such database management operations, you can also use the SQL*Plus utility to start/stop the database if srvctl is
unable to complete the job.
The following cluster command stops the database:
# srvctl stop database -d RONDB
In contrast to a RAC and Non-RAC database, starting the RAC One Node database has something new to offer.
On instance failure or stop, Oracle will randomly select an eligible candidate server from the predefined candidate
server list to bring up the instance automatically. Presuming that Node A and Node B are listed in the candidate
server, and the database is running on Node A prior to instance failure or startup, the instance will pick either a
different server or the same server from the list to start a replacement instance. Therefore, under some circumstances,
there will is no guarantee in the context that the new instance will restart on the same node.
When you want to start the database on a particular node using the srvctl utility, you must use the
-n
argument to
specify the name of the node on which the database should start. For automatic instance failover, Oracle might select
the candidate server in the order displayed in the config output.
Use the following example to start up the database:
$srvctl start database -d RONDB -n rac1
Performing Online Database Relocation
Just for a moment, imagine yourself in any of the following circumstances surrounding common maintenance activity:
•
You are planning a prolonged maintenance activity on the database server
•
The node on which your RAC One Node database is running becomes overloaded, running
out of resources and capacity
•
You are applying Oracle patches on the node
