ORA-01200: actual file size of string is smaller than correct size of string blocks
Cause: The size of the file as returned by the operating system is smaller than the size of the file as indicated in the file header and the control file. Somehow the file has been truncated. Maybe it is the result of a half completed copy.
Action: Restore a good copy of the data file and do recovery as needed.
ORA-00265: instance recovery required, cannot set ARCHIVELOG mode
Cause: The database either crashed or was shutdown with the ABORT option. Media recovery cannot be enabled because the online logs may not be sufficient to recover the current datafiles.
Action: Open the database and then enter the SHUTDOWN command with the NORMAL or IMMEDIATE option.