oracle 11g retrieve dbid while database is not able to mount
SQL- alter session set tracefile_identifier ='Block_dump';
alter system dump datafile '/u01/app/oracle/oradata/ORADBT/system01.dbf' block min 1 block max 10 ;
SQL- alter system dump datafile '/u01/app/oracle/oradata/ORADBT/system01.dbf' block min 1 block max 10;
alter session set tracefile_identifier=off;
/u01/app/oracle/diag/rdbms/oradbt/ORADBT/trace