I think there's one cache file for each role not for each user so you won't get 2.5 Tb of cache unless you have one role per user but it doesn't make sense.
I've got a site with about 65000 nodes with only anymous visitor :
~/web/pwet.fr/www$ du -sh var/plain/cache/content/plain_site_user/
154M var/plain/cache/content/plain_site_user/
Moreover, ViewCaching is almost mandatory if you want good performance on your site.
and i've checked it: there is a separate cache file for each user visited this node.
Probably it is not a good practice to show user name in a template for a node, but anyway: my calculations are correct so i can expect such cache size in the future.
if this template is or is used in a view template with ViewCaching enabled it should not work as expected unless each user has different roles assignments. That's why showing user information is generally made in the pagelayout template.
If you look at the generateViewCacheFile method in kernel/classes/eznodeviewfunctions.php you will see that the cache file name depends on :
- node id
- view mode
- language
- offset and other view parameters
- layout
- user's roles and limitation - preferences if configured for that
so basically, for a given page two users will "share" a cache file if they have the same role assignments.
