My takeaway from this is maybe somewhat different from what the authors intended:
> The last one? Our friend, cassandra-messages. [...] To start with, itβs a big cluster. With trillions of messages and nearly 200 nodes, any migration was going to be an involved effort.
To me, that's a surprisingly small amount of nodes for message storage, given the size of discord. I had honestly expected a much more intricate architecture, engineered towards quick scalability, involving a lot more moving parts. I'm sure the complexity is higher than stated in the article, but it makes me wonder, given that I've been partially responsible for more than 200 physical nodes that did less, how much of modern cloud architecture is over engineered.
They are talking about 177 database nodes, which is not an indicator of architecture complexity. I assume they have dozens/hundreds of services consisting of multiple highly available nodes each across various geographies.
Having seen a much smaller set of Cassandra nodes used to store billions (rather than trillions) of records, I can say that Cassandra was definitely a total PITA for on-call, and a cause of several major outages.
> ...how much of modern cloud architecture is over engineered.
I would wager a good majority of it is. The Stack Overflow architecture[0] sticks out to me in this regard as an example on the other end of the spectrum.
> The last one? Our friend, cassandra-messages. [...] To start with, itβs a big cluster. With trillions of messages and nearly 200 nodes, any migration was going to be an involved effort.
To me, that's a surprisingly small amount of nodes for message storage, given the size of discord. I had honestly expected a much more intricate architecture, engineered towards quick scalability, involving a lot more moving parts. I'm sure the complexity is higher than stated in the article, but it makes me wonder, given that I've been partially responsible for more than 200 physical nodes that did less, how much of modern cloud architecture is over engineered.