How do I move my storage node onto a new hard disk? how long to wait before I can graceful exit?

[Alexey]

@SGC

and is done to get the remaining held amount paid out.

I could only add - you can receive a final payout on L1 only if it clear a Minimum Payout Threshold on Ethereum.
However, you can opt-in for zkSync or Polygon to make it happen in the next payout.

But in general - the Graceful Exit is a one way ticket.