IBM DBCA-203240, Specifications, Page: 19 / 190

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.
m a x
S U M ( m a x + 1
Ä
n ) ( T n . i n + T n . o u t )
n = 1
W e i g h t e d A v e r a g e =
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
( m a x + 1 ) ( m a x )
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
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
Figure 8. Full Stroke Seek Time
Full stroke seek is measured as the average of 1000 full stroke seeks.
3.3.5 Average Latency
Figure 9. Latency Time
Function Typical Max
R E A D 2.5 msec 4.0 msec
Write 3.0 msec 4.5 msec
Function Typical Max
Read 23.0 msec 30.0 msec
Write 24.0 msec 31.0 msec
RPM Time for a revolution Average Latency
4200 14.3 msec 7.1 msec
Drive Characteristics
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