IBM Ultrastar 36LZX, Specifications

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4.5 Performance characteristics
A drive’s performance is characterized by the following parameters:
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Command overhead
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Mechanical head positioning
- Seek time
- Latency
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Data transfer speed
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Buffering operation (read ahead/write cache)
NOTE: All the above parameters contribute to drive performance. There are other parameters that contri-
bute to the performance of the actual system. This specification tries to define the bare drive character-
istics, not the system throughput, which depends on the system and the application.
4.5.1 Command overhead
Command overhead is defined as the time required:
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from last byte of command phase
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to the first byte of data phase
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excluding
- Physical seek time
- Latency time
- Initiator delay with reconnections
<30 usec Cache Hit
<400 usec Cache Not Hit
Time Read Command Case (Drive is in quiescence state)
Figure 6. Command overhead
Ultrastar 36LZX hard disk drive specifications
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