A couple thoughts from a Librato founder here:<p>- Appreciate the thorough and balanced approach you took here, there's a lot of great feedback, most of which helps validate our current roadmap and 1-2 things we'll certainly consider.<p>- The tradeoff of providing a true utility service where you only pay for what you use is that the actual makeup of your bill can become complex (think of your AWS bill). We do pro-rate usage to the hour right now (matching AWS), so unless your metric "lifetimes" are sub-hour there's shouldn't be a huge issue.<p>- There's a similar power/complexity tradeoff with rollups. Unlike some solutions that only rollup via average we track multiple summary statistics e.g. min, max, sum, count, weighted average. Managing the differences between these can be confusing in some cases, so we're currently working on a simpler interface to toggle between these. More details can be found here: <a href="https://www.librato.com/docs/kb/visualize/faq/rollups_retention_resolution.html" rel="nofollow">https://www.librato.com/docs/kb/visualize/faq/rollups_retent...</a><p>- Mobile support is something we've been incrementally adding and will continue until it's complete e.g. the actual alerts page you land on from a notification is now mobile-ready.<p>- Tagging. In the years since we first launched (when AFAIK only OpenTSDB supported this) it's become clear that this is becoming more and more a standard capability. Which is why we've been building out a next-generation data-store, which supports indexed tagging and a bunch of other new capabilities. We expect it to be in beta this summer.
We went on the hunt for a time-series data-store a while ago and ended up picking OpenTSDB. It seems they are planning on supporting Cassandra (which sounds like it will be easier to maintain than HBase): <a href="http://opentsdb.net/docs/build/html/user_guide/backends/cassandra.html" rel="nofollow">http://opentsdb.net/docs/build/html/user_guide/backends/cass...</a>
Another worthy contender was KairosDB: <a href="https://kairosdb.github.io/" rel="nofollow">https://kairosdb.github.io/</a>