- Core is in Java

- License - not sure?

- OpenTSDB used for storing time series, HBase 0.98.8

- Stores extended schema (entities, alerts, state) in another database (derby, postgres, not sure?). Why not Phoenix.

- Namespace concept used for grouping metrics

Joins a lineup of internal time series database projects, some of which are OSS now: Netflix Atlas, StackExchange Bosun, Facebook Gorilla.