/READAHEAD (Default)
       /NOREADAHEAD

    When a disk read is required to fill a cache block, /READAHEAD
    specifies that the read is to be from the first block requested
    to the end of the bucket boundary. Readahead can speed up
    sequential operations by pre-loading disk blocks that are needed
    into the cache.

    If you specify both /READAHEAD and /READBEHIND, any block
    requested within a cache bucket causes the entire bucket range
    of blocks to be read into the cache.