Let's take a look at the throughput of a server hard disk vs. a typical server CPU: https://serverfault.com/questions/190451/what-is-the-throughput-of-15k-rpm-

Let's take a look at the throughput of a server hard disk vs. a typical server CPU: https://serverfault.com/questions/190451/what-is-the-throughput-of-15k-rpm-sas-drive https://serverfault.com/questions/190451/what-is-the-through... https://www.anandtech.com/show/9185/intel-xeon-d-review-performance-per-watt-server-soc-champion/6 https://www.anandtech.com/show/9185/intel-xeon-d-review-perf... Now, that 45.8 GB/sec can't usually be fully utilized by the application, but it's a lot higher than the 200MB/sec of the server hard drive. There's also the complication of RAID, max memory fetch rate of a single core, etc. And the fact that the database has to do some processing besides moving data around. But it seems to me that server CPU bandwidth of the last generation is significantly higher than spinning disks.