This SSD speed explainer has interactive diagrams to help you understand I/O latency

I wish I had access to this explainer from Planetscale back when I was learning how different storage technologies work, rather than scratching my head at Wikipedia pages and Reddit ‘explain like I’m five’ threads that often seemed more like ‘explain like I’m an engineer’ ones.

I think this is probably the best explanation of different storage technologies and their respective latency problems that I’ve come across. And if, like me, you struggle a little with the (boring, let’s face it) nitty gritty, but really get something out of visualisation and simple, big picture explanations, I think you’ll agree.

The article is actually a long-form pitch for the company’s latest cloud solution, but you won’t see that up until right near the end, and until then, it’s great for anyone looking to learn more about storage. It guides us through the three main storage types of the last few decades—tape, HDDs, and SSDs—and what causes read/write latency in each solution.

(Image credit: Planetscale)

As the article explains: “The removal of mechanical components reduces the latency between when a request is made and when the drive can fulfill the request. There is no more waiting around for something to spin.”

The part I found the most interesting and useful was the explanation of how SSDs can still have problems with latency and how these can be solved. Essentially, latency can be improved by having data written to or read from different targets simultaneously, in parallel, rather than having data coming from or going to just one target, one set of blocks of data. Reorganising data that needs to be deleted so it’s next to other data that needs to be deleted can also cause slow-down.

All this is much easier to understand with the animated diagrams, though.

Apart from all this, the diagrams also help show just how ridiculously fast SSDs are compared to HDDs, and certainly compared to tape. The simple back-and-forth moving data diagrams show just how quickly pages or cells of data are read or written with each storage technology, and each new technology really is orders of magnitude quicker than the one before.

We know that, of course, but it’s something else to see that visually represented so simply. All well worth a look if you’re interested in understanding what makes our modern storage tick and what slows it down.