If you don't need to keep data forever, but only several weeks or months, and you only need numeric time series data and not raw event logs, Prometheus (http://prometheus.io/) is your friend. Since it's optimized towards purely numeric time series (with arbitrary labeled dimensions), it currently uses an order of magnitude less disk space than InfluxDB for this use case, and I've also heard a few reports of people's CPU+IO usage dropping drastically when they switched from InfluxDB to Prometheus for their metrics.

As dashboards for Prometheus, you can currently use PromDash (http://prometheus.io/docs/visualization/promdash/), Console HTML templates (http://prometheus.io/docs/visualization/consoles/), or Grafana (http://prometheus.io/docs/visualization/grafana/).

Durable long-term storage is still outstanding. Although replication into OpenTSDB and InfluxDB is experimentally there.