ORA-01618: redo thread 2 is not enabled - cannot mount & ORA-1613 Error.

RAC Duplication was performed in our database and then we changed the cluster_database=TRUE, and tried to startup the RAC database using SRVCTL command.

First instance Comes Up without any issues but when 2nd instance was trying to come up it fails in the mount stage with the errors. 

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#   Errors 
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Alert Log Info :

ORA-1618 signalled during: ALTER DATABASE   MOUNT...

ORA-01618: redo thread 2 is not enabled - cannot mount

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#   Command Used  
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srvctl start database -d mydb

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#   Informations  
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Initially what i thought is that Redo Thread 2 is not Enable, so i tried to enable it with the below command, which gave me ORA-1613 Error. 

http://stepintooracledba.blogspot.com/2013/03/ora-1613-signalled-during-alter.html

alter database enable public thread 2;

With further investigation found whats the issue.


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#  Solution 
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  Error says that Redo Thread 2 Cannot be Enabled. So to Enable Redo Thread we need REDO LOGS, When i checked the Redologs in our database,  i Can see we have 12 Redo Groups all belongs to Thread 1, 

But Actually we have allocated 6 Redo logs to Thread 1 and 6 Redo Logs to Thread 2.  

So Added Redo Log Groups to thread 2 and enabled the thread and it got completed without any issues.

Command Used To Add Redo Logs to thread 2 :

alter database add logfile thread 2 group 7
('/u01/oradata/mydb/redo_02_07.log') size 1024M;

Now Opening the database with srvctl doesnt give any error and both the instances were UP & Running.