/ITEM=(keyword[,...])

    Selects one or more data items for inclusion in display and
    summary outputs. If you specify two or more keywords, enclose
    them in parentheses, and separate them with commas. When the
    /ITEM qualifier is omitted, the default is /ITEM=OPERATION_RATE.

    The following table describes /ITEM qualifier keywords:

    Keyword       Description

    ALL           Specifies that statistics on all data items
                  collected for the disks are displayed on successive
                  screens.

    OPERATION_    Specifies that I/O operation rate statistics are
    RATE          displayed for each disk.

    QUEUE_LENGTH  Specifies that the number of I/O request packets
                  being serviced (current or waiting) is displayed
                  for each disk.