Shortest Seek Time First (SSTF)

Service all requests close to the current head position together, before moving the head far away to service another request. This policy is similar to shortest job first. After each request is received, the controller selects the request that is closest to the current location of the head. The throughput is much better than in FIFO. However, some process may have to wait long time until it's request(s) are satisfied if new requests with shorter seek time keep arriving.

Example:

Total number of tracks covered: 236.
Problems: May cause starvation to some requests, since requests may arrive at anytime.
Disadvantages

• starvation is possible; stay in one area of the disk if very busy.
• switching directions slows things down