ORA-01619: thread 1 is mounted by another instance

The following problem may appear when patching the Oracle Grid Infrastructure:

If so, the solution for the problem is the following. You need to find out which node of the RAC is failing to startup. Once you have found out, you need to run the following command on that node (probably in nomount/mount state, locally direct on the specific instance):

alter system set thread=4 scope=spfile sid=’orcl4';

The thread parameter should be one of the available threads in the cluster. You can find that information from the following query:

SQL> select thread#, sequence#, status from v$log;

Then you should  shutdown the instance and retry:

[oracle@dbnodt1 ~]$ srvctl start database -d dbtiso