Check out KairosDB... it is based on Cassandra and is very similar to OpenTSDB but IMO Cassandra is a bit easier to scale and maintain with fewer parts. We're

Check out KairosDB... it is based on Cassandra and is very similar to OpenTSDB but IMO Cassandra is a bit easier to scale and maintain with fewer parts. We're using it in production... it's still early but there are about 1-2 dozen moderate sized installs (like 10 box installs). We're pretty happy with it so far..