What backup application software do you use? It should have an option to validate your data, but I agree with Carlos that a test restore is the only way to 100% guarantee it is good. It’s just not likely you can do a test restore for every backup every day. We have 800 servers, not a possibility!
I don’t actually have the idea about the term test restores. However, in terms of ensuring your important files from you back up tapes or drives have some factors you have to consider. These factors are the following:
Proper Storage – it is very important to store your backup storage device in a dry and away from high temperature areas. This is to ensure that there is no heat which could affect the little hardware parts of the device.
Proper Handling – it is also very important to consider the proper handling of the storage device to avoid from outside physical shocks and bumps.