Introduction to Riak as log storage and querying logs. Fluentd is casual, easy daemon to collect and aggregate logs from many servers, many daemons. In popular use cases, fluentd outputs collected log to HDFS, S3 or MongoDB. Riak is scalable and casual distributed key value store with rich query interface, and easy to operate, scale, manage and query. Useful logging patters and query tools in Ruby-ish way will also be introduced.