Why can't you use LocalDb in a Windows Azure Website

Question

Regardless of whether it is a good idea or not, why is LocalDb not supported in Windows Azure Websites? I'd like to understand the technical reasons.

Answer 1

Properly designed cloud applications need to be essentially stateless.

Introducing any local, stateful storage (a designated place to "hold the truth" that is not distributed and discrete), is a scary prospect from an architecture standpoint.

If using local DB, unless you could guarantee through load balancers or other tech that all instances will always use that specific web server, you could end up with inaccurate data once you scale.

Furthermore, during an operation where the Web Sites service is going to update the host OS or guest OS that hosts your Web Site, it might actually spin up an additional Web Site (though you are only charged for 1) during that operation that will help handle requests during the downtime in order to maintain SLA. What would happen in that scenario to the data resiliency?