As the team behind the raintank platform explores various time series database solutions, they initially dismissed MongoDB and MySQL due to their unsuitability for handling large-scale time-series data. OpenTSDB's complexity and Graphite's backend issues led them to discover InfluxDB, an open-source database that impressed with its ease of installation, performance, and support for the Carbon plaintext protocol. InfluxDB, written in Go, performed well under significant load, handling over 50,000 metrics per second without becoming a bottleneck, though it faced challenges with listing series performance. Despite this, InfluxDB's promising development and recent $8 million Series-A financing suggest a strong future, while the team also considers exploring Cassandra and KairosDB for their platform.