I am trying to setup Craft to use a memcached (yes it is memcached, not memcache) cluster in AWS ElastiCache to handle sessions. I originally went the route of updating my php.ini file in Apache2 to override the PHP session save handler and session save path. That worked at first, but I found that sometimes memcached would seem to return null if a session object was being accessed around the same time. After running into that error a bunch and not being able to resolve it, I decided to try setting up memcached through Craft.
My question is does Craft default to local file storage if it can't connect to my memcached cluster? The reason I think this is happening is because if I use the overridePhpSessionLocation, I can tell that it isn't working because I am getting timed out on my site since we store the timeout in the session. However, when I set overridePhpSessionLocation to 'auto', and then put all the proper information in my memcache.php file, the site seems to work. But if I screw up the hostname in the memcache.php file, the site still works. So what is going on? Is Craft defaulting to local file storage when there is a connection issue or is there something else happening?