My computer contains two NTFS hard disks. Until recently, the machine ran Windows 98, and I used the second disk as a backup by making it an inactive system disk, then making it active if the boot drive crashed or became infected with a virus. When I used Fdisk to format the backup disk, I had the option of adding the system files to the disk or running the Sys X: command to transfer the files to the backup disk. However, I recently upgraded the system to Windows 2000, and when I installed the OS and reformatted the second disk, I saw no mention of the system files. How do I make the backup disk a system disk in Win2K?

To understand what constitutes booting in Win2K, you need to understand a few basic processes. These processes are BIOS-related events, system startup (involving Windows NT Loader—NTLDR), and kernel loading (followed by user logon).

In addition to maintaining hardware configurations, the BIOS also finds the Master Boot Record (MBR) and loads it into memory. This load is important because the MBR scans the partition table, finds the system partition, and loads sector 0 of the system partition into memory. The system partition must be on disk 0; the system directory or boot partition isn't necessarily on the system's first drive and can be on an extended or primary partition of any BIOS- resident drive. The system drive (i.e., the drive containing the system directory) is typically the drive that contains the \winnt directory.

After the BIOS loads the MBR and the MBR finds and loads sector 0 of the system partition into memory, the Boot Loader phase takes place. During this phase, NTLDR is responsible for booting into Win2K. NTLDR switches memory to 32 bit and reads the appropriate file format (i.e., FAT or NTFS). NTLDR loads and reads boot.ini, which then appears on screen. The user chooses a boot.ini option (such as running Win2K). When the option is a Win2K or NT derivative, the boot process loads ntdetect.com, which gathers information about attached hardware. NTLDR then loads again and starts ntoskrnl.exe or the Win2K or NT kernel.

As the kernel loads and initializes, the device drivers load and the Win2K system fully initializes. The monitor switches to graphic mode and winlogon.exe loads, opening the Logon window. After the user logs on, all required services start up.

When you understand this boot process, it becomes evident that only three files—NTLDR, boot.ini, and ntdetect.com—need to be in a startup disk's root directory. To format your second disk as a backup disk, first install Win2K on the primary disk. Next, copy boot.ini from the primary disk to a neutral directory (you'll need to change the file's attributes before you copy the file). Then, complete a second installation in an identically named directory on the second disk and overwrite that installation's boot.ini file with the copy you saved. If you want to add software to disk 0, you need to install the same software to the same locations on both disks. (If you don't like dual installations, you can use Symantec's Norton Ghost to copy the primary disk to the backup disk. Doing so will forgo the need to install additional software or files on disk 1.) Make certain that identical versions of boot.ini, NTLDR, and ntdetect.com are in both disks' root directories. After ensuring that both disks contain the necessary three files, remove the second disk and use it only when absolutely essential.

If viruses are your primary concern, you can simply format a 3.5" disk in Win2K and copy boot.ini, NTLDR, and ntdetect.com to that disk. Make the disk read-only so that no viruses can infect it, then use that disk as a boot backup.