VMS Help V73 Features, System Management Features, Extended File Cache (Alpha)  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    The Extended File Cache (XFC) is a new virtual block data cache
    provided with OpenVMS Alpha Version 7.3 as a replacement for the
    Virtual I/O Cache.

    Similar to the Virtual I/O Cache, the XFC is a clusterwide, file
    system data cache. Both file system data caches are compatible
    and coexist in an OpenVMS Cluster.

    The XFC improves I/O performance with the following features that
    are not available with the Virtual I/O Cache:

    o  Read-ahead caching

    o  Automatic resizing of the cache

    o  Larger maximum cache size

    o  No limit on the number of closed files that can be cached

    o  Control over the maximum size of I/O that can be cached

    o  Control over whether cache memory is static or dynamic

    For more information, refer to the chapter on Managing Data
    Caches in the OpenVMS System Manager's Manual, Volume 2: Tuning,
    Monitoring, and Complex Systems.