A viable replacement for rrd for storing timeseries data

We've played around with:<p>OpenTSDB: <a href="http://opentsdb.net/" rel="nofollow">http://opentsdb.net/</a><p>StatsD: <a href="https://github.com/etsy/statsd/" rel="nofollow">https://github.com/etsy/statsd/</a> (description here - <a href="http://codeascraft.etsy.com/2011/02/15/measure-anything-measure-everything/" rel="nofollow">http://codeascraft.etsy.com/2011/02/15/measure-anything-meas...</a>)<p>OpenTSDB and StatsD seemed great for getting TS data in and producing nice dashboards, but they didn't seem to fit our needs for performing custom analytics on the data.<p>At the moment, we're leaning towards leveraging Cassandra based on our scalability requirements. Check out <a href="http://rubyscale.com/blog/2011/03/06/basic-time-series-with-cassandra/" rel="nofollow">http://rubyscale.com/blog/2011/03/06/basic-time-series-with-...</a> and <a href="http://www.datastax.com/dev/blog/advanced-time-series-with-cassandra" rel="nofollow">http://www.datastax.com/dev/blog/advanced-time-series-with-c...</a> to get an idea on how cassandra can help.

i have seen this ppt and it looks inspiring <a href="http://www.slideshare.net/sky_jackson/time-series-data-storage-in-mongodb" rel="nofollow">http://www.slideshare.net/sky_jackson/time-series-data-stora...</a>