вот что говорит сам Оракель
Цитата: oerr ORA 01200
01200, 00000, "actual file size of %s is smaller than correct size of %s 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
// controlfile. 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.
Действительно случай смертельный для этой базы.
Сделать тут только одно - восстановить из архива.