 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
• |
The
disk arm starts at one end of the disk, moves
|
|
toward
the other end, servicing requests until
|
|
|
reaching
end of disk, then the head reverses and
|
|
|
servicing
continues.
|
|
|
|
– |
i.e.
Pick the closest request in same direction as last
|
|
|
arm
motion
|
|
|
• |
Con
– more arm motion than SSTF
|
|
|
• |
Pro
|
|
|
|
– |
Fair
|
|
|
|
– |
Avoids
starvation
|
|
|
• |
Example
total head movement of 208 cylinders.
|
|