"Tectonic (Pan et al., 2021), Meta’s general-purpose distributed file system, is used to build a storage fabric (Battey and Gupta, 2024) for Llama 3 pre-training. It offers 240 PB of storage out of 7,500 servers equipped with SSDs, and supports a sustainable throughput of 2 TB/s and a peak throughput of 7 TB/s"

I would expect at least 10s if not 100s TB/s from a cluster of 7500 servers with SSDs, what is the bottleneck?