[dikei]

>> functional partitioning is a band-aid.

I disagree, functional partitioning is not a band-aid, but an architectural changes that in the end can reap much more benefit than simple data sharding.

>> your whole site is dependent on every single functional partition being up. it moves you from 1 single point of failure to N single points of failure!

Not necessarily, it can also be that only some parts of your site are dead while others work perfectly fine.

[throwusawayus]

too idealistic. invariably some team (or usually many teams) don't properly gate some critical-path logic, they depend on some functional partition always being online and then boom much larger blast radius than intended

then they fix it in post-mortem but pattern just repeats. i have seen it so many times! used to be much worse in the earlier days of the cloud when VMs would go poof more often