ORA-01157: cannot identify/lock data file and ORA-01110

 ORA-01157 error along with ORA-01110 in alert log file means that a datafile that DBWR is trying to access (to read or write) is no longer available. One reason coule be that this file was accidentally removed, or file permissions were accidentally changed, thus hindering oracle processes to read/write this datafile. Another reason could be the file system - where this dataifle existed - is no longer mounted or available.

ORA-01017: invalid username/password during dataguard switchover

 If you have configured dataguard broker and you are performing database switchover using DGMGRL command, you should make sure that you connect with dataguard broker using a privileged user and supply password instead of using a forward slash (‘/’) to log  in and initiating the switchover. If you do not follow this procedure, you would be returned ORA-01017 because a privileged session with both primary and physical standby is required to initiate switchover (or failover). Following is an example of receiving the error.

Switchover to Physical Standby Database Using Dataguard Broker DGMGRL

Switching over to standby database when you are using dataguard broker is a very straightforward operation. You just need to initiatie dgmgrl command prompt, check status of standby database and simply issue switchover command. Always remember to log in to DGMGRL using password, not ‘dgmgrl /’. Otherwise you will receive ORA-01017. Also make sure that password file of primary was successfully copied to standby database after your last SYS password reset, otherwise you may face ORA-16467 during switchover.