I was playing with the Fronzen times and I see that the data is deleted and never goes from warm to cold (I think in this state the data is compressed right?
How can I make my data go from warm to cold after 3 months?
I believe data is rolled on the size basis from warm to cold.
So you can estimate the per day data traffic and then for 90 days and set the parameter, maxWarmDBCount accordingly and data will start rolling automatically from warm to cold depending on size.
Also, yes data reduction/compression happens while data retention.