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ORA-01210:

data file header is media corrupt
Cause: The file header block is internally inconsistent. The beginning of the block has a header with a checksum and other data for insuring the consistancy of the block. It is possible that the last disk write did not operate correctly. The most likely problem is that this is not a datafile for any database.
Action: Have operating system make correct file available to database. If the trace file dump indicates that only the checksum is wrong, restore from a backup and do media recovery.