Great question — answering as the UphillTech team:
You can use Graphite / Whisper database to store high volume metrics (6 Millions per min). You need to mention proper Archival and Retention policy in Whisper. Also Graphite database is highly scalable so you can add more CPU or I/O. Graphite Whisper document
Full answer by Vikram Shinde: https://stackoverflow.stackexchange.com/a/45324876 (CC BY-SA 3.0).
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