Single Track Seek Time; Full Stroke Seek; Average Latency - IBM DBCA-204860 - Travelstar 4.8 GB Hard Drive Specifications

The seek time is measured from the start of motion of the actuator to the start of a reliable read or write
operation. Reliable read or write implies that error correction/recovery is not employed to correct for arrival
problems. The Average Seek Time is measured as the weighted average of all possible seek combinations.
W e i g h t e d A v e r a g e =
W h e r e :
m a x = M a x i m u m S e e k L e n g t h
n = S e e k L e n g t h ( 1 t o m a x )
T n . i n = I n w a r d m e a s u r e d s e e k t i m e f o r a n t r a c k s e e k
T n . o u t = O u t w a r d m e a s u r e d s e e k t i m e f o r a n t r a c k s e e k

3.3.3 Single Track Seek Time

Function
READ
Write
Figure 7. Single Track Seek Time
The single track seek time includes settling time but does not include command overhead.
Single track seek is measured as the average of one (1) single track seek from every track in both directions
(inward and outward).

3.3.4 Full Stroke Seek

Function
Read
Write
Figure 8. Full Stroke Seek Time
Full stroke seek is measured as the average of 1000 full stroke seeks.

3.3.5 Average Latency

RPM
4200
Figure 9. Latency Time
m a x
S U M ( m a x + 1 n ) ( T n . i n + T n . o u t )
n = 1
( m a x + 1 ) ( m a x )
Time for a revolution
14.3 msec
Typical
2.5 msec
3.0 msec
Typical
23.0 msec
24.0 msec
Max
4.0 msec
4.5 msec
Max
30.0 msec
31.0 msec
Average Latency
7.1 msec
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Drive Characteristics