After reboot of both the RAC nodes, we encountered “ORA-01105: mount is incompatible with mounts by other instances” & “ORA-19808: recovery destination parameter  mismatch” oracle error, after diagnosis i came to know about the size of the db recovery parameter, i.e. db_recovery_file_dest_size is mismatch over the nodes.

After setting identical size of the db recovery file destination, infected node up and running smooth as expected.

Error Logs:

 SQL> startup;
 ORACLE instance started.
 Total System Global Area 4275781632 bytes
 Fixed Size 2235208 bytes
 Variable Size 1694500024 bytes
 Database Buffers 2566914048 bytes
 Redo Buffers 12132352 bytes
 ORA-01105: mount is incompatible with mounts by other instances
 ORA-19808: recovery destination parameter mismatch

DB recovery parameter ‘db_recovery_file_dest_size’ verification on 2nd instance by issuing the following command:

 SQL> show parameter recovery
 NAME TYPE VALUE
 ------------------------------------ ----------- ------------------------------
 db_recovery_file_dest string +DATA
 db_recovery_file_dest_size big integer 150G
 recovery_parallelism integer 0

DB recovery parameter ‘db_recovery_file_dest_size’ verification on 1st instance by issuing the following command:

 SQL> show parameter recovery
 NAME TYPE VALUE
 ------------------------------------ ----------- ------------------------------
 db_recovery_file_dest string +DATA
 db_recovery_file_dest_size big integer 100G
 recovery_parallelism integer 0

According to above verification logs, highlighted area mismatched over the RAC nodes.

Workaround: Set ‘db_recovery_file_dest_size’ at 2nd instance to 100GB, as follows:

SQL> alter system set db_recovery_file_dest_size = 100G scope=spfile;
 System altered.

Bounce 2nd instance by normal shutdown and restart, as follows:

SQL> shutdown

 ORA-01507: database not mounted
 
 ORACLE instance shut down.

SQL> startup
 ORACLE instance started.
 Total System Global Area 4275781632 bytes
 Fixed Size 2235208 bytes
 Variable Size 1694500024 bytes
 Database Buffers 2566914048 bytes
 Redo Buffers 12132352 bytes
 Database mounted.
 Database opened.

By above workaround, Infected node up and running smooth.

 SQL> select inst_name from v$active_instances;
 INST_NAME
 ------------------------------------------------------------
 database1:>>Instance_I<<
 database2:>>Instance_II<<

Stay Tune 🙂