A. In earlier versions of Windows, you had to manually enable certain physical and logical disk counters before their values could be monitored via tools such as performance monitor. In Windows 2003 and XP, both sets of counters are automatically enabled, and no manual configuration is required. Microsoft notes that for legacy applications that use the IOCTL_DISK_PERFORMANCE control code to retrieve raw counters, you can specify -Y or -N on the Diskperf command to forcibly respectively enable or disable the counters, as you could with previous versions of Windows.