Keep data forever - issue #1287 - Part 2

(from github.com/julianopcardoso)
A question about keeping data: I would like keep my data (modified or not) and removing from index only excluded documents from base, How do I must configure it?

Actually I have this configuration, but I lost all data, for the first time after one month, even tough crawler running everyday at 10p.m.:
Check Last Modified: Enabled
Remove Documents Before: 3 Day(s)

(from github.com/marevol)

Remove Documents Before: 3 Day(s)

-1 is that documents are not expired.