N-Step-SCAN is a disk scheduling

I/O scheduling

Input/output scheduling is a term used to describe the method computer operating systems decide the order that block I/O operations will be submitted to storage volumes...

 algorithm to determine the motion of the disk's arm and head in servicing read and write requests.
It segments the request queue into subqueues of length N. Breaking the queue into segments of N requests makes service guarantees possible. Subsequent requests entering the request queue won't get pushed into N sized subqueues which are already full by the elevator algorithm.
As such, starvation is eliminated and guarantees of service within N requests is possible.

Analysis

N-Step-SCAN along with FSCAN

FSCAN

FScan is a disk scheduling algorithm to determine the motion of the disk's arm and head in servicing read and write requests.It uses two subqueues. During the scan, all of the requests are in the first queue and all new requests are put into the second queue. Thus, service of new requests is...

 prevents "arm stickiness" unlike
SSTF

Shortest seek first

Shortest seek first is a secondary storage scheduling algorithm to determine the motion of the disk's arm and head in servicing read and write requests.- Description :...

, SCAN

Elevator algorithm

The elevator algorithm is a disk scheduling algorithm to determine the motion of the disk's arm and head in servicing read and write requests....

, and C-SCAN.

See also

Other variations include:

• SCAN
  Elevator algorithm
  The elevator algorithm is a disk scheduling algorithm to determine the motion of the disk's arm and head in servicing read and write requests....
  
   - Elevator Algorithm
• FSCAN
  FSCAN
  FScan is a disk scheduling algorithm to determine the motion of the disk's arm and head in servicing read and write requests.It uses two subqueues. During the scan, all of the requests are in the first queue and all new requests are put into the second queue. Thus, service of new requests is...
  
  
• LOOK
  LOOK algorithm
  LOOK is a disk scheduling algorithm used to determine the order in which new disk read and write requests are processed.-Description:LOOK is similar to SCAN in that the heads sweep across the disk surface in both directions performing reads and writes...
  
  (and C-LOOK)