Memcached with failover for session store?


It seems that its clear that memcached by itself for session storage has
one weakness when it came to long lasting sessions (lets say, days,
weeks or months). What happens is that is delete stored objects to set
new objects when the memory is near its maximum operational limit (and
that is not the max memory you defined).

So, does anyone knows how to solve that issue or to have memcached with
an alternative (file or db based) session store for failover when a
cache miss is encountered? Or, at least just for the session failover?