Comment by scottlamb

I don't think people are upvoting this for the fact at the top of "say something surprising" [1], but it indeed surprised me:

> I can write 500MB/s to a hard drive? that's so much!

Turns out a Seagate 2X18 can write at 528 MiB/s according to its spec sheet. [2] My rule of thumb was that HDDs could do like 100MB/s (aka 800 Mbps) but I guess between density improvements and this new "dual-actuator" class, it's gotten a lot faster. HDD seek time has basically been stuck for 30+ years and probably will remain so but capacity has increased a lot, and the throughput for sequential access probably should scale with capacity [edit: times rpm, thanks Retr0id]. For a while I think it wasn't increasing, but I guess they decided to fix that?

SSDs of course can do way more than 500 MB/s, and you can do better by compressing as you write (depending on your data), and you can stripe across multiple HDDs, but it turns out none of those are necessary.

[1] as I write this, the title "no feigning surprise" suggests <https://wizardzines.com/comics/no-feigning-surprise/> but the link points to "say something surprising" <https://wizardzines.com/comics/surprise/>.

[2] https://www.seagate.com/www-content/datasheets/pdfs/exos-2x1...