Several questions about durable object

I have three questions about durable object:

  1. As I know the durable object has no data center? Then how can it ensure data will never be discarded? We want to build a test project based on it, and I am quite curious about the redundant replica distribution. If we mainly invoke in China, will the distributed redundant nodes be closer to China or be globally distributed?
  2. I know, for one object, transaction can be achived by memory operation. But I wanna know if transactional application between different objects is allowed?
  3. How often will memory data be stored to disk? And How often will the data be replicated to redundant nodes?

Durable Objects do live in data centers. When a new Durable Object is created, it is spun up in the nearest DO-compatible colo. When you operate on the persistent storage, changes are saved in multiple colos - this means a DO can still be accessed if a colo is rerouted.

Writes are saved to disk when you await the operation or return a response.

Though please note Durable Objects are still in beta, so data loss may occur.