IBM DTLA-307075 Hard Drive Specifications - Page 25

Full stroke seek, without command overhead, including settling, Head switch time Head skew

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Seek time is measured from the start of the 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 used to correct arrival problems. The average seek time is measured as the weighted average of all possible seek combinations. Weighted average = max Sum (max+1-n) (Tn.in+Tn.out) n=1 (max+1) (max) where max = Maximum seek length n = seek length (1 to max) Tn.in = Inward measured seek time for an n track seek Tn.out = Outward measured seek time for an n track seek 4.4.2.2 Full stroke seek (without command overhead, including settling) Function Read Write Typical (ms) DTLA-305XXX DTLA-307XXX 16.7 14.7 18.3 15.7 Max (ms) DTLA-305XXX DTLA-307XXX 19.7 17.7 21.3 18.7 Figure 6. Full stroke seek time Full stroke seek is measured as the average of 1000 full stroke seeks with a random head switch from both directions (inward and outward). 4.4.2.3 Head switch time (Head skew) Head switch time DTLA-305XXX DTLA-307XXX Typical (ms) 1.5 1.2 Figure 7. Head switch time Head switch time is defined as the amount of time required by the fixed disk to complete a seek of the next sequential track after reading the last sector in the current track The measuring method is given in 4.4.6 "Throughput" on page 0. Deskstar 40GV & 75GXP hard disk drive specifications 13

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Seek time is measured from the start of the 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 used to correct arrival
problems.
The average seek time is measured as the weighted average of all possible seek combi-
nations.
Weighted average =
(max+1) (max)
max
Sum
n=1
(max+1-n) (Tn.in+Tn.out)
where
max = Maximum seek length
n = seek length (1 to max)
Tn.in = Inward measured seek time for an n track seek
Tn.out = Outward measured seek time for an n track seek
4.4.2.2
Full stroke seek
(without command overhead, including settling)
18.7
21.3
15.7
18.3
Write
17.7
19.7
14.7
16.7
Read
DTLA-307XXX
DTLA-305XXX
DTLA-307XXX
DTLA-305XXX
Max
(ms)
Typical
(ms)
Function
Figure 6. Full stroke seek time
Full stroke seek is measured as the average of 1000 full stroke seeks with a
random head switch
from
both directions (inward and outward).
4.4.2.3
Head switch time (Head skew)
1.2
DTLA-307XXX
1.5
DTLA-305XXX
Typical
(ms)
Head switch time
Figure 7. Head switch time
Head switch time is defined as the amount of time required by the fixed disk to complete a seek of the
next sequential track after reading the last sector in the current track
The measuring method is given in 4.4.6 “Throughput” on page 0.
Deskstar 40GV & 75GXP hard disk drive specifications
13