Tradeoff: how much complexity

Tradeoffs in implementation complexity

Lots of knobs in the NBD spec Mandate all-or-none server implementation

Pro

Implement as much or as little as convenient for the server
Matches reality that no one resize solution fits all

Easier interoperability testing
Client can rely on all servers giving same response

Con

More combinations requires more testing
Odd or untested combinations could produce weird behaviors or even CVEs
Clients must be prepared for more fallbacks
NBD protocol tries to be as simple as possible

Not all tradeoffs map easily to existing implementation
Open-ended structured replies requires more efforts for writing a compliant server

	Lots of knobs in the NBD spec	Mandate all-or-none server implementation
Pro	Implement as much or as little as convenient for the server Matches reality that no one resize solution fits all	Easier interoperability testing Client can rely on all servers giving same response
Con	More combinations requires more testing Odd or untested combinations could produce weird behaviors or even CVEs Clients must be prepared for more fallbacks NBD protocol tries to be as simple as possible	Not all tradeoffs map easily to existing implementation Open-ended structured replies requires more efforts for writing a compliant server