Things get a little extra complicated here, because we're mixing units-notice the big B in MB/sec, and the small b in Gbps. You're also limited by the bandwidth of your controller and cabling-for example, modern SATA links typically operate at 6Gbps, while modern SAS links can operate up to 22.5Gbps. If you've got a single head on a conventional rust disk spinning at 7200RPM, the rate you can get data on or off that disk will be limited by the number of physical sectors/blocks passing beneath the head. There are several choke points in a storage system for throughput-first and foremost, there's the speed of the physical medium itself.
Throughput, measured most commonly in storage systems in MB/sec, is the most commonly used way to talk about storage performance. Throughput, latency, IOPS and cache Throughput We're going to walk you through some simple but effective uses of fio on Windows, Mac, and Linux computers-but before we do that, let's talk a little bit about storage systems from a more basic perspective. Fortunately, we don't have to invent such a tool-there's already a free and open source software tool called fio, and it's even cross-platform! So we do want an artificial benchmarking tool-but we want one that we can use intelligently to test storage systems across realistic scenarios that model our day-to-day usage well. Unfortunately, that's neither very repeatable, nor is it simple to analyze. The most realistic way to test and benchmark disks is, of course, to just use them and see what happens. Unfortunately, the actual workload of a typical disk doesn't look like that-and that "simple speed test" doesn't reproduce a lot of the bottlenecks that slow down disk access in real-world systems. Admins and enthusiasts have for decades been tempted to just "get the big number" by reading or writing a large amount of data to a disk, getting a figure in MB/sec, and calling it a day. Further Reading How Ars tests Wi-Fi gear (and you can, too)Storage benchmarking-much like Wi-Fi benchmarking-is a widely misunderstood black art.
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