That's not quite the issue - SSI (which I didn't know about!) sounds cool, but it's a programming model that solves similar issues at a different abstraction la

That's not quite the issue - SSI (which I didn't know about!) sounds cool, but it's a programming model that solves similar issues at a different abstraction layer. The question that remains unsolved is, regardless of what abstraction you use, whether the overhead of communication (latency, throughput) between nodes is large enough to make things annoying, and whether it's possible to work around this effectively or not. Stuff like InfiniBand along with tech like RDMA is helping a lot with this, and hardcore database installations do use this.