Because I had run out of disk space and my SCSI disks were old and obsolete, I needed to replace a domain controller's (DC's) mirror volume, which was composed of two SCSI disks, with a RAID 1 array, which was composed of two IDE disks and an IDE RAID adapter. The mirror volume was also the system and boot volume.
My plan was to install the new IDE RAID adapter without installing the new disks so that Windows 2000 didn't know they existed, install the proper Win2K drivers, shut down the machine, install the new disks and configure the new array, use a disk-cloning product (e.g., Symantec Ghost) to copy the mirror volume to the new RAID 1 array, remove the old disks, then boot the new installation. (If you ever need to clone dynamic disks, you should know that Ghost has some compatibility problems. For more information about these problems, see "Ghost compatibility with dynamic partitions" at http://service1.symantec.com/support/ghost.nsf/docid/2000062209523525.)
I ran into some problems because the system and boot volume's drive letter was E rather than C (the C drive didn't exist). When I first booted from the new array, Win2K recognized the newly installed mirrored disks as the C drive. Because the server was a DC, Active Directory (AD) wouldn't start. Therefore, I couldn't start the newly configured machine, even in Directory Services Restore Mode.
The Microsoft article "HOW TO: Change the System/Boot Drive Letter in Windows" (http://support.microsoft.com/?kbid=223188) provides a solution. To correct the situation, I reconnected the old mirror volume and booted from it to let Win2K recognize the new disks. I then ran regedt32, loaded the SYSTEM hive from the new disks, and renamed the registry value DosDevices\C to DosDevices\E. As the Microsoft article mentions, this values is in the HKEY_LOCAL_MACHINE\SYSTEM\MountedDevices registry subkey. Finally, I shut down the server, removed the SCSI disks, and booted successfully to the new installation. (If you have other problems booting from a mirror volume, see the Microsoft articles "Booting From Mirror After Primary Partition Is Lost" at http://support.microsoft.com/?kbid=113977 and "Steps to Recover a Failed Mirrored System/Boot Partition" at http://support.microsoft.com/?kbid=120227.)