IBM DJSA-210 Hard Drive Specifications - Page 27

Performance characteristics, 5.1 Command overhead - djsa 220

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4.5 Performance characteristics File performance is characterized by the following parameters: ! Command Overhead ! Mechanical Positioning ! Seek Time ! Latency ! Data Transfer Speed ! Buffering Operation (Look ahead/Write Cache) Note: All the above parameters contribute to file performance. There are other parameters which contribute to the performance of the actual system. This specification defines the essential file characteristics. This specification does not include the system throughput as this is dependent upon the system and the application. The following table gives a typical value for each parameter. The detail descriptions are found in section 5.0. Function Average Random Seek Time For Read (ms) Average Random Seek Time For Write (ms) Rotational Speed (RPM) Power-on-to-ready (sec) Command overhead (ms) Disk-buffer data transfer (Mb/s) Buffer-host data transfer (MB/s) (PIO Mode-4) (Ultra DMA Mode-4) Typical DJSA-232 12 13 5400 5.0 1.0 120-223 16.6 66.6 Typical DJSA-230 12 13 4200 3.3 1.0 109-203 16.6 66.6 Typical DJSA-220/210/205 12 13 4200 3.0 1.0 109-203 16.6 66.6 Figure 6. Performance characteristics 4.5.1 Command overhead Command overhead time is defined as the interval from the time that a drive receives a command to the time that the actuator starts its motion. Travelstar 33GH/30GT/20GN hard disk drive specifications 13

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4.5 Performance characteristics
File performance is characterized by the following parameters:
!
Command Overhead
!
Mechanical Positioning
!
Seek Time
!
Latency
!
Data Transfer Speed
!
Buffering Operation (Look ahead/Write Cache)
Note: All the above parameters contribute to file performance. There are other parameters which contri-
bute to the performance of the actual system. This specification defines the essential file characteristics.
This specification does not include the system throughput as this is dependent upon the system and the
application.
The following table gives a typical value
for each parameter. The detail descriptions are found in
section 5.0.
16.6
66.6
16.6
66.6
16.6
66.6
Buffer-host data transfer (MB/s) (PIO Mode-4)
(Ultra DMA Mode-4)
109–203
109-203
120-223
Disk-buffer data transfer (Mb/s)
1.0
1.0
1.0
Command overhead (ms)
3.0
3.3
5.0
Power-on-to-ready (sec)
4200
4200
5400
Rotational Speed (RPM)
13
13
13
Average Random Seek Time For Write (ms)
12
12
12
Average Random Seek Time For Read (ms)
Typical
DJSA-220/210/205
Typical
DJSA-230
Typical
DJSA-232
Function
Figure 6. Performance characteristics
4.5.1 Command overhead
Command overhead time is defined as the interval from the time that a drive receives a command to the
time that the actuator starts its motion.
Travelstar 33GH/30GT/20GN hard disk drive specifications
13