The picture below is from a computer backup I was doing over the network.
This was with the existing file on the target drive being overwritten. For new files the transfer rate is nearly constant and a little above the peak shown here.
I suspect the algorithm used by either the driver or the controller for the hard disk for update an existing file results in a large number of seeks of the head. The file copy program (Robocopy in this case) could work around the problem by deleting existing files before doing the copy. But the designers of the program may not have been aware of the problem with this particular hard drive.
In my situation I don’t care a lot because it can just run as a background task and it doesn’t much matter if it takes 10 minutes or 300 minutes (yes, the transfer rate is over 30x slower). But for some people it might.
As always, thoroughly testing your products, processes, and assumptions is important and either this one wasn’t fully tested or management marked the bug as “Won’t Fix” and shipped it anyway.
Having presided over numerous Boomerite failures I know how easy it is to say, “This change shouldn’t matter” or “This has to make it better, no need to test it.” There is a reason many companies have a test team that is independent of the development team and may even have a reporting chain independent of engineering.
This, almost, paranoia about testing can be generalized to a lot of things in your life. Have you ever changed a tire on your current vehicle? I bought a used vehicles a few years ago and discovered a day or so after I bought it that it didn’t have a jack in it.
You have a gun to defend your home and loved ones? Have you ever pied the corners of your home with that shotgun? Have you looked at possible choke points for stopping a home invasion? How about looked at what happens to misses or shoot-throughs from likely shooting positions? How do those speed reloads you practice for USPA matches work out for you when you are at the top of the stairs in your birthday suit?
Progressives want the government to have more power to implement “social justice”. Ask the tens of millions of people that went into the Gulags of the USSR how that worked out for them. Oh, that’s right, most of them that weren’t shot after their forced confessions were worked and starved to death. We don’t need to run that test again. 100+ million people have already been killed during the testing done by various progressives regimes in the 20th century.
Anti-gun people want to register guns. Ask Canada how that worked out for them.
Does your bug-out kit included canned goods but you forgot to include a can opener?
You’ll discover many such things when you test.