The amount of time to retain a cross-Region snapshot or AMI copy. The maximum is 100 years. This is equivalent to 1200 months, 5200 weeks, or 36500 days.
The unit of time for time-based retention. For example, to retain a cross-Region copy for 3 months, specify Interval=3 and IntervalUnit=MONTHS.
Interval=3
IntervalUnit=MONTHS