IIRC, the most recent and most technical public content we (Google) have published on Colossus are these:

https://cloud.google.com/blog/products/storage-data-transfer...

https://cloud.google.com/blog/products/storage-data-transfer...

Facebook's published content on Tectonic is quite good and I think it's well more recent than 2010-14.

(Current Google employee, just pointing to public content, hope that's helpful.)