[ksec]

The reason was that I remember DHH stating they were doing 2K RPS with 30 App Server in 2015 ~ 2016. And they were on one Primary DB. ( At least that was what I jot down in my notes ). I was assuming they could fit multiple "App Server" Node inside a single 1U Blade. But even if it was 1U per App Server, that would be 30U + likely a Powerful 4U DB Monster. Along with probably some Cache instances.

Even if the number above does not include redundancy, that still only makes it 2 Racks of Servers with spare.

30 Racks is a lot. What am I missing here? Apart from Storage.

[wlll]

The place I work (CTO for now, looking for opportunities pretty soon) can sustain nearly 400 RPS through a Rails app on a single Performance-L Heroku dyno without a sweat (though we run two min), but it's the tip of the iceberg. The infra to support those web servers is way more than that. Aurora Postgres x 3 for now, a large ES cluster, 2x redis clusters, memcached etc.

Bear in mind that we had I think 6 apps. Basecamp 1, 2 and 3 (all separate infra), Highrise, Campfire, some other internal stuff. Our ES cluster was pretty damn big, redis and memcached too. Juniper, F5, network switches (rack infra) etc. Storage was pretty big, quite a few 4u servers with spinning rust. The blade servers were I think 6 blades in 2u.

Everything was redundant, everything had 2x or more. I honestly can't remember how many racks we had. "More than 10" is my hand-wavey guess.

I don't think DHH was being disingenuous with his "2k on 30 servers" message, it was likely more about the scalability of Rails rather than the infra required to run the app.

[flakeoil]

Do you guys define racks the same way?

[wlll]

I think so, 42U of full-depth server capacity.