Yesterday I was asked by a customer for the reason why he had
failed to achieve scale with a state-of-the-art "shared-storage"
cluster. "It's a scale-out to 4 servers, but with a shared disk.
And I got, after tons of work and efforts, 130% throughput,
not even close to the expected 400%" he said.
Well, scale-out cannot be achieved with a shared storage and the word "shared" is the key. Scale-out is done with absolutely nothing shared or a "shared-nothing" architecture. This what makes it linear and unlimited. Any shared resource, creates a tremendous burden on each and every database server in the …