Oracle : Ошибка 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.

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