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

There is a buffer that contains very fast memory that the drive can write on to. The buffer is made of volatile memory that’s very fast to read and write from, but is cleared when power is removed; once that buffer is filled you can only write to it as fast as the persistent memory on the drive allows you to.