One important recommendation: please do not run benchmarks on variable-performance storage (gp2 in this case), as it obviously may yield different performance depending on the credit situation, potentially delivering more or less performance to different benchmark runs / scenarios.
Specifically, for 500GB you get the max throughput (250MB/s, which BTW is pretty low for an OLAP-style bench, in my opinion) but only 1.5K IOPS. See [1] for more information.
An easy alternative would have been gp3 volumes, which do not burst performance, and can be set to provide 16K IOPS and 1Gbps.
[1] https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/general-...