When planning for disaster recovery there are two different issues which need to be addressed. These issues are related but really quite different. That is data recovery and business continuity.
If you lost your data due to a fire or other disaster you could recover it almost immediately with the use of a simple off site back up. That is data recovery. You would have the data but your business would still not be running unless you could access the data in a useful way. That second phase is business continuity.
To use the recovered data you will need a computer (ultimately a whole computer network) configured in roughly the same fashion as the lost hardware. You will need all the software including networking, links or data bridges installed and configured with the same versions and preferences as the system which was lost. In most cases that means installing from the original disks (if you can find them). You will need product codes and passwords.
With a good backup you could have the data immediately. However it could take a technician days to install and configure a computer to use the data.