/sys$common/syshlp/helplib.hlb SET, VOLUME, Qualifiers, /DATA_CHECK  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /DATA_CHECK[=(option[,...])]

    Defines a default for data check operations following all read
    and write operations to the specified volume. (If you do not
    specify the /DATA_CHECK qualifier, no checks are made.) Possible
    keywords are as follows:

    READ    Performs checks following all read operations.
    WRITE   Performs checks following all write operations (default).