Usage: sg_rbuf [--buffer=EACH] [--dio] [--echo] [--help] [--mmap]
               [--quick] [--size=OVERALL] [--time] [--verbose] [--version]
               SG_DEVICE
  where:
    --buffer=EACH|-b EACH    buffer size to use (in bytes)
    --dio|-d        requests dio ('-q' overrides it)
    --echo|-e       use echo buffer (def: use data mode)
    --help|-h       print usage message then exit
    --mmap|-m       requests mmap-ed IO (overrides -q, -d)
    --quick|-q      quick, don't xfer to user space
    --size=OVERALL|-s OVERALL    total size to read (in bytes)
                    default: 200 MiB
    --time|-t       time the data transfer
    --verbose|-v    increase verbosity (more debug)
    --old|-O        use old interface (use as first option)
    --version|-V    print version string then exit

Use SCSI READ BUFFER command (data or echo buffer mode, buffer id 0)
repeatedly. This utility only works with Linux sg devices.