Setup /r allows you to recover an existing Exchange server to new hardware. It assumes that you have a valid backup of the Exchange databases and does not generate any default (empty) databases. After running setup /r, you must restore the Exchange databases from backup.
Setup /r is known as a forklift upgrade—use it to move a server to a different computer or to restore to a new computer. For example, your server is destroyed (asteroid) and you get a new computer to replace it. While you are at it, you want to move up to a newer, faster x86 or maybe to an Alpha computer. After you have the spiffy new computer, you need a full backup of the directory service and information store. If you are merely upgrading, you can shut down the original server and proceed. If your old server was indeed destroyed by a natural disaster and you don't have a full backup tape (because you kept it near the computer and it, too, was destroyed), you can just go on home.
But if you do have the full backup, you can proceed. First configure the new computer with Windows NT. Then run setup /r to install the Exchange software but not start any of the services or initialize the directory service into a site and so on. Now restore the backup to the new server and start the services. The new computer comes up and starts running just as the old computer did.
