I have spent a little time each year over decades planning a library. The first draft planned a shipping container full of rack-mounted equipment, and several more shipping containers full of the equipment to power the library. That version never got built.
My current iteration uses a bunch of 18 TB HDDs in a HP Z-series workstation.
If I had the money to actually deploy prototypes outside my home, I would switch to much more power efficient SATA SSDs, a Raspberry Pi, some kind of hat that connects many SATA drives, and a low-power Wi-Fi router that connects many users at once.
Over the years I learned that: * The US Library of Congress (LOC) cataloging system is the best way to index information, but... * Databases are temporary. Files on disk are much more permanent. You will change databases several times while leaving the same files on disk.
LLMs will change my design, as will StarLink and other satellite-based Internet Service Providers (ISPs)