/sys$common/syshlp/helplib.hlb Sys Parameters, VBN_CACHE_S  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    (VAX only) This special parameter is used by Compaq and is
    subject to change. Do not change this parameter unless Compaq
    recommends that you do so.

    The static system parameter VBN_CACHE_S enables or disables file
    system data caching. By default its value is 1, which means that
    caching is enabled and the Virtual I/O Cache is loaded during
    system startup.

    Setting the value to 0 disables file system data caching on the
    local node and throughout the OpenVMS Cluster. In an OpenVMS
    Cluster, none of the other nodes in the cluster can cache any
    file data until this node either leaves the cluster or reboots
    with VBN_CACHE_S set to 1.