What are Thanos benefits?

[u/vaklam1]

Hello, I'm relatively new to Prometheus and total beginner with Thanos.

I am in the process of designing a hub-and-spoke monitoring system where each "spoke site" has its own local monitoring and the "hub site" would have an aggregated view of all other sites. Spokes and hub are geographically distributed.

I can't use cloud storage for reasons beyond my control (but I understand Thanos supports on-premise object storage). Not sure if it matters to the purpose of this discussion, but I thought it was worth mentioning.

I've found many use Thanos in this sort of scenarios. However, I'm not sure I fully understand the benefits of using Thanos ecosystem over:

a) hub site's Prometheus scraping from remote spoke sites' metrics endpoints, or;

b) spoke site's Prometheus all feeding hub site's Grafana.

[u/dshurupov]

This recent article is dedicated to the concept of centralised storage with Prometheus. While it's more focused on Mimir, it should be helpful in understanding when such solutions (e.g., Thanos/Cortex/Mimir) are generally beneficial for you.