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# Hard Drive - Seek Time, Write Time, and Latency - Looking for clarification

Posted on 2013-01-30
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These are the Seek Time, Write Time, and Latency specs for my old hard drive (Seagate Momentus 7200.4 ST9500420ASG 500GB 7200 RPM).

Average Seek Time = 11ms
Average Write Time = 13ms
Average Latency = 4.17ms

What's the total Read Time? Here's my guess:
Average Total Read Time = Average Seek Time + Average Latency
Is this correct?

What's the total Write Time? Here's my guess:
Average Write Time = Average Write Time  + Average Latency
Is this correct? Or, do I omit Latency because it's already included in the Average Write Time?
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Question by:jdana
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Duncan Meyers earned 652 total points
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Yes - latency is typically one half of a rotation. Total read time should include settling time and the time to read a sector. Your calculation for write time is correct assuming that the specs have included seek time in the write time. If not, you need to add average seek time.

It's quite a slow drive. A 10k enterprise drive has latency around 3.5mS and average seek times around 2.5mS.
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nobus earned 648 total points
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Author Closing Comment

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Thanks!
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ID: 38923999
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