When Redo Log Files Are All Missing

If your redo logs are all missing, then you have to know you will lose some data and no longer to recover it. Now let's mount the database, I mean you can only startup the database to mount state, and let the control file knows all the situation.
SQL> startup mount;
ORACLE instance started.
...
Database mounted.
Recover the database until cancel
SQL> recover database until cancel;
...
CANCEL
Open the database with resetlogs which implies that we discard all of the missing redo logs and  try to start it over.
SQL> alter database open resetlogs;

Database altered.
Check the redo logs again
[oracle@test ~]$ ll /u01/app/oracle/oradata/compdb
...
-rw-r-----. 1 oracle oinstall  52429312 Apr 13 19:05 redo01.log
-rw-r-----. 1 oracle oinstall  52429312 Apr 13 19:04 redo02.log
-rw-r-----. 1 oracle oinstall  52429312 Apr 13 19:04 redo03.log
The database recreates all required redo log files when opens with resetlogs.