When copying from USB or external drive, why does it starts very fast and suddenly drops transfer rate by up to 50% and stays there? Why it can’t be speed as in the beginning all the time?

Question

Is it a hardware limitation or calculation algorithm problem, until enough data is transferred to calculate exact speed?

In: 14

Answer 1

Oversimplified:

Imagine you’re transcribing a recorded speech by hand. You would not write each letter (err sound) as you hear it – you would write (most likely) each sentence/paragraph at a time. The transcription process consists of hearing and writing – in that order.

The progress on completing a sentence would be largely consumed by the writing – but the progress ‘bar’ (metaphorically) would begin at the moment you began listening to the sentence, and end once you finished writing the sentence. The speed with which the progress bar would move would be incredibly fast at the beginning (hearing) but then would slow down when you began writing the sentence.

So, in this analogy –

You: Computer
Speech: Data for copy job (USB)
Listening: speedy initial progress on copy job
Writing: slowdown on progress
Transcription: copy job