Migration from single instance to RAC database, can be done in two ways depending if downtime is possible:

1. Creating Physical Standby database
2. Restore template with DBCA on another server
3. Using the RConfig

In our case we will use the RConfig tool. So let's get going

First, be sure to take an offline backup of the single instance database, preferably with RMAN:

$ rman target /
$ shutdown immediate;
$ startup mount;
$ backup database;
$ alter database open;
</Code<

In case the database has a standby increase archivelog apply gap:

<Code:bash|Increase archivelog gap>
[oracle@enode01 ~]$ sqlplus / as sysdba
SQL> alter system set archive_lag_target=7200 scope=both; 
System altered. 
SQL> exit
[oracle@enode01 ~]$
<Code>

After that, let's modify the template so we can test if everything is set up correctly.
Bare in mind that a configured clusterware should be available on both servers with ASM.

{{ :singleinstance2rac.jpg?400 |}}

First locate the "ConvertToRAC_AdminManaged.xml" in the $ORACLE_HOME/assistants/rconfig/sampleXMLs and copy it:

<Code:bash|Modify the template>
[oracle@enode01 sampleXMLs]$ cp ConvertToRAC_AdminManaged.xml 
ConvertToRAC_AdminManaged.bkp 
[oracle@enode01 sampleXMLs]$
[oracle@enode01 sampleXMLs]$ vi ConvertToRAC_AdminManaged.xml
<?xml version="1.0" encoding="UTF-8"?> 
<n:RConfig xmlns:n="http://www.oracle.com/rconfig" 
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
 xsi:schemaLocation="http://www.oracle.com/rconfig rconfig.xsd"> 
 <n:ConvertToRAC> 
<!-- Verify does a precheck to ensure all pre-requisites are met, before the 
conversion is attempted. Allowable values are: YES|NO|ONLY --> 
 **<n:Convert verify="ONLY">** 
<!--Specify current OracleHome of non-rac database for SourceDBHome --> 
 
<n:SourceDBHome>/u01/app/oracle/product/12.1.0/dbhome_1</n:SourceDBHome> 
<!--Specify OracleHome where the rac database should be configured. It can be 
same as SourceDBHome --> 
 
<n:TargetDBHome>/u01/app/oracle/product/12.1.0/dbhome_1</n:TargetDBHome> 
<!--Specify SID of non-rac database and credential. User with sysdba role is 
required to perform conversion --> 
 <n:SourceDBInfo SID="eastdb"> 
 <n:Credentials> 
 <n:User>sys</n:User> 
 <n:Password>oracle_4U</n:Password> 
 <n:Role>sysdba</n:Role> 
 </n:Credentials> 
<!--Specify Windows Secure Oracle Home Credentials if the Oracle Home was 
installed with Secure User option -->