Verifying That Instances are Running

To verify that a database instance is available, use Oracle Enterprise Manager, SRVCTL, or SQL*Plus.

Using SRVCTL to Verify That Instances are Running

You can use SRVCTL to verify that instances are running on a particular database.

The following command provides an example of using SRVCTL to check the status of the database instances for the Oracle RAC database named mail:

$ srvctl status database -db mail

This command returns output similar to the following:

Instance mail1 is running on node betal011Instance mail2 is running on node betal010

Additionally, you can check whether PDBs are running in the cluster by checking the availability of their assigned services, as follows:

$ srvctl status service -db db_unique_name -service service_name

You can use SQL*Plus to verify that database instances are running.

On any node, from a SQL*Plus prompt, connect to a database instance by using a Net Services connection string, typically an instance-specific alias from your tnsnames.ora file.
```
CONNECT /@db1 as SYSDBA
```

Query the V$ACTIVE_INSTANCES view, using the following statement:

CONNECT SYS/as SYSDBA
Enter password: password
SELECT * FROM V$ACTIVE_INSTANCES;

This query returns output similar to the following:

INST_NUMBER INST_NAME    
-----------  ----------------- 
1            db1-sun:db1  
2            db2-sun:db2  
3            db3-sun:db3

The output columns for this example are shown in Table 3-2.

Table 3-2 Descriptions of V$ACTIVE_INSTANCES Columns

Column	Description
`INST_NUMBER`	Identifies the instance number.
`INST_NAME`	Identifies the host name and instance name as `host_name`:`instance_name`.