Backing Up and Restoring the Cisco IOS
Before you upgrade or restore a Cisco IOS, you really should copy the existing file to a TFTP
host as a backup just in case the new image crashes and burns.
But before you back up or restore an IOS image, you need to check these things:
Make sure you can access the network server.
Ensure that the network server has adequate space for the code image.
Verify the file naming and path requirement.
The copy flash tftp command must be supplied with the IP address of the workstation
if you are copying from the router flash.
And if you’re copying “into” flash, you need to verify there’s enough room in flash memory
to accommodate the file to be copied.