Can storage move without the user knowing?

RESEARCH QUESTION

Moving data between performance tiers transparently sounds straightforward until you ask what happens to a request that arrives for a file in the middle of being moved. The logical namespace is supposed to stay stable regardless of where the bytes physically live — but “stable” has to hold up under concurrent access, not just at rest.

The specific question we’re exploring: what’s the right behavior for a read or write that targets a file mid-migration? Blocking until the move completes is the simplest answer, but it reintroduces exactly the kind of latency spike that transparent placement was supposed to eliminate. Serving from the old location until the move is confirmed complete is another option, but it means briefly tolerating two authoritative copies, which has its own consistency implications if a write happens to either one during that window.

We haven’t settled on an approach, and we’re deliberately not claiming one works until it’s been tested under real concurrent load rather than reasoned about on a whiteboard. This is early enough that the honest status is: open question, candidate approaches identified, no result yet.