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

    Attempts to switch from the current path of a multipath device
    to the path named in the /PATH qualifier. The path switch
    is attempted only if the path has not been disabled by SET
    DEVICE/NOENABLE. The path switch is initiated but not completed
    before returning control to the user; use SHOW DEVICE/MULTIPATH
    to verify that the path switching has completed successfully.