How can C-SCAN (elevator) algorithm cause starvation?

Question

I'm reading Silberschatz's OS book. In section 16.8.1 it says:

The fundamental problem with the elevator algorithm is that I/O operations cocentrated in a specific region of the disk can result in starvation of requests that need to occur in other regions of the disk.

The C-SCAN algorithm, processes all sectors in order, as illustrated on this web page.
I don't understand how this could cause some requests to wait indefinitely.

Answer 1

If you look at Silberschatz's Operating System Concepts 7th edition you'll find that n exercise 7.5's answer he says starvation "the situation whereby a process must wait beyond a reasonable period of time—perhaps indefinitely—before receiving a requested resource." so SCAN and C-SCAN may spend an awful long time near one hot region of the disk before getting back to a starving area somewhere else. The starvation doesn't have to be a permanent denial of service.

Answer 2

It could be made to wait indefinitely if the same sector were requested over and over. The disk would be stuck servicing that one sector forever.