Riak memcache backend configuration

app.config

 %% Riak KV config
 {riak_kv, [
            %% Storage_backend specifies the Erlang module defining the storage
            %% mechanism that will be used on this node.
            %% {storage_backend, riak_kv_bitcask_backend},
            {storage_backend, riak_kv_multi_backend},

            {multi_backend_default, <<"eleveldb_mult">>},
            {multi_backend, [
                {<<"eleveldb_mult">>, riak_kv_eleveldb_backend, [
                    {data_root, "./data/leveldb"},
                    {max_open_files, 512}
                ]},
                {<<"memcache_15min">>,    riak_kv_memory_backend, [
                    {max_memory, 512},
                    {ttl, 900}
                ]},
                {<<"memcache_30min">>,   riak_kv_memory_backend, [
                    {max_memory, 1024},
                    {ttl, 1800}
                ]},
                {<<"memcache_2h">>,   riak_kv_memory_backend, [
                    {max_memory, 2048},
                    {ttl, 7200}
                ]}
            ]},