We have come up with a Not so elegant solution. 1. Install php-memcached, Now you have 2 clients side by side. 2. Write with both the client, php-memcache(cA) and php-memcached(cB), cB will have a certain prefix. Read from cA. 3. After cache is warmed up. start reading from cB. 4. upgrade/change hash to cA. 5. Let the cache warm up. 6. Start reading from cA. 7. retire cB.
But this would guarantee that the memcache is always available.
