(Alpha and Integrity servers) The dynamic system parameter VCC_
    READAHEAD controls whether the extended file cache can use read-
    ahead caching. Read-ahead caching is a technique that improves
    the performance of applications that read data sequentially.

    By default VCC_READAHEAD is 1, which means that the extended file
    cache can use read-ahead caching. The extended file cache detects
    when a file is being read sequentially in equal-sized I/Os, and
    fetches data ahead of the current read, so that the next read
    instruction can be satisfied from cache.

    To stop the extended file cache from using read-ahead caching,
    set VCC_READAHEAD to 0.

    Changing the value of VCC_READAHEAD affects volumes currently
    mounted on the local node, as well as volumes mounted in the
    future.

    Readahead I/Os are totally asynchronous from user I/Os and only
    take place if sufficient system resources are available.

    VCC_READAHEAD is a DYNAMIC parameter.