I've got about 40000 posts and I'm using mod_rewrite cache.
Only Single Posts (is_single), Pages (is_page), Front Page (is_front_page) and Feeds (is_feed) is cached.
I've currently put 0 in Expiry Time and have built my own program that deletes feeds and front page manually every 10 minutes.
In my situation, I would rather like to use garbage collection, but not for Single Posts and Pages. Only for Front Page and Feeds.
If I put 600 in Expiry Time and check "Preload mode". Will Single Posts and Pages be untouched, and Front Page and Feeds garbage collected?
The docs say: "In ’Preload Mode’ regular garbage collection will only clean out old legacy files for known users, not the preloaded supercache files. This is a recommended setting when the cache is preloaded."
As you can see, I'm not sure what this means. What does "legacy files" mean? And how do you define "known users"?
And I also wonder how smart your garbage collection is. Will it loop thru all my 40000 cached posts every time, or is it smarter than that?