I'm in the Financial services industry.
There is a regulation requirement to keep financial data for 5 years.
But what would be the recommended retention for backup files and logs?
You may find that the standard changes according to the country that you reside in. This is due to the Laws and Regulations.
In Canada and the US, it is stipulated that records need to be kept for five (5) years, however GDPR and SEC state that some records must be kept for seven (7) years.
Here's an article on the topic: