ORA-01157: cannot identify/lock data file %s - 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-01110: data file %s: '%s'
 *Cause:  Reporting file name for details of another error. The reported
          name can be of the old file if a data file move operation is
          in progress.
 *Action: See associated error message.