Will there be a chapter about how your preferred architecture compares to in-memory databases technologies? SAP has been creating a lot of marketing hype on this in the last years. Indeed I think a lot of business problems can be solved by cramming more RAM into centralized servers. Yesterday's big-data problems are now routine if you have a dozens-of gigabytes of RAM machine available.
Or is this question not applicable at all (because the architecture makes no assumptions on the type of data storage); the requirements and usage scenarios are completely different?
The architecture described in the book is fully distributed and horizontally scalable, and I won't be looking at scale-up techniques. The chapters on Storm and distributed RPC does have an emphasis on using lots of RAM for certain tasks though by partitioning data appropriately across the nodes.
Or is this question not applicable at all (because the architecture makes no assumptions on the type of data storage); the requirements and usage scenarios are completely different?