Comment by orochimaaru
18 hours ago
I don't think the global transaction router is a GLB. Having dabbled in this for high traffic telemetry gathering infrastructure, I will hazard a guess and say the "router" isn't a GLB.
The router needs to be shard-aware. It needs to know what data is where based on the request coming in so that it can route accurately. A GLB is DNS. It cannot be shard-aware because all it knows is the FQDN being resolved.
It can be a "router" if all the router needs to know is to resolve to the nearest data center or the nearest CDN. But at that point I have to ask the question - why does one need a cell-based architecture and can't it just be geo-redundant active-active failover across regions.
In any sense, the architecture itself isn't novel or new. It's documented here: https://docs.aws.amazon.com/wellarchitected/latest/reducing-.... It's the go to model if you're running a cloud.
Active/active without sharding is not a horizontal scaling model, and the blast radius of a fault is wide.
One can have GLBs that do routing. So long as the tenant-to-cell routing tables are consistent, it works fine. And those mappings tend not to change frequently.