You could e.g. use Logstash's metrics plugin to emit a per-minute rate (there's an example in its documentation). I haven't really used Redis so I'm not sure how to measure the inbound rate (unless you can measure on the producing side, i.e. whatever's feeding Redis). You could of course use something as simple as a redis-cli call in a shell script loop to see the length of the list that Logstash pulls from. With a bit of arithmetic you can figure out the inbound rate since you know the outbound rate and the growth rate.