Absolutely astounding to me, petabytes an hour? That's in the region of a meg to several megs per user per hour looking at their monthly active user figures.
Basically, everything that needs logging and post-processing by both real-time systems (e.g. Puma) and batch processing (e.g. all of the data that's ingested and sent to the data warehouse) goes through Scribe.
(disclaimer: I work in Scribe)
Scuba: https://research.fb.com/publications/scuba-diving-into-data-...
Puma: https://research.fb.com/publications/realtime-data-processin...