ORA-01157:cannot identify/lock data file string – see DBWR trace file
Cause: The background process was either unable to find one of the data files or failed to lock it because the file was already in use. The database will prohibit access to this file but other files will be unaffected.
However the first instance to open the database will need to access all online data files. Accompanying error from the operating system describes why the file could not be identified.
Action: Have operating system make file available to database. Then either open the database or do ALTER SYSTEM CHECK DATAFILES.
ORA-01111 & ORA-01110 datafile unknown/missing problem
SQL> RECOVER DATABASE USING BACKUP CONTROLFILE;
SQL> startup mount
if in the AIX operating system or UNIX base, you can check :
set ulimit -1 on /etc/security/limits (User oracle)
because database can’t access the datafile which have size more than 1G.