Recent Wildly Fluctuating Copy Speeds of Large Files (125+ GB) to External Hard Drives

I failed to think of posting images of what I am experiencing, so I am just sharing what I should have shared in the beginning if I had been bright enough to do so.

They say that "a picture is worth a thousand words." These are images of Teracopy's status and log reports from today's copy of my weekly backup image (this week, it was a Macrium Reflect image). I will also be sharing these images over at my topic at Bleeping Computer, the link to which can be found in the next paragraph. That topic was opened after the many experts here could not find a way to help me to explain or resolve it, despite their best efforts, for which I am grateful.. It is no closer to resolution over at Bleeping Computer.

Wildly Fluctuating Copy Speeds When Copying Large Image Files - Windows 11

I have been critical of a certain member here for posting the same topic in multiple Forums simultaneously, so I think it best to make sure my nose is clean!

Copy_Speed_Fluctuations_Graph by Philip Campbell, on Flickr

Copy_Speed_Fluctuations_Log by Philip Campbell, on Flickr

It still seems to me that it might indicate buffer flushing or a change in the way Windows reports copy speeds when dealing with large files . . .

Have a great day.

Regards,
Phil

One thing that I just realized that I did not mention.

TeraCopy had a couple of issues with certain hash verification algorithms, in both v3.10 and 3.12, that caused idiosyncrasies, including crashes.


3.10 was released 4 July, and 3.12 was released 29 September.

Additionally, there is this specific item about slow speeds in 3.12:


CodeSectore does have a v3.16 Beta version (released 19 November) that you can give a shot:


Or, you can try the previous 3.9.7 stable release:

@johnlgalt ,

Thank you for your reply. I really appreciate the research. I can't express my gratitude with a"Helpful" yet because it appears I have temporarily exceeded my 24-hour quota, but I will be back!

During the copy yesterday of that 138.6 GB Macrium Image file, the speeds varied from 2.9 MB/s to 264 MB/s on a cyclic basis. Unfortunately, because the copy operation took 24:03, the graph does not show the wide range of speed fluctuations.

I did install "Fast Copy" to test it, but it was slower than Teracopy, so I uninstalled it. I saw the same cyclic phenomenon using it as I do with TeraCopy Pro and the File Explorer copy function.

My computer is just a plain Dell XPS 8930 SE (see my Computer 1 specs), so I don't think it is being afflicted with the TeraCopy bug that has been reported.

I long for the good old days when my copy speed took off initially and then settled down to a nice steady 100 MB/s, plus or minus 10 MB/s.

Thanks again, John. Have a great day.

Regards,
Phil

Lol - no worries - I don't live for the reactions.

Looking forward to hearing how the alternate versions affect (or don't) the roller-coaster transfers.

garioch7 said:

I did install "Fast Copy" to test it, but it was slower than Teracopy, so I uninstalled it.

Click to expand...

I wonder why. For me Fast Copy is slightly faster than Teracopy when copying to my Mini PC over Wi-Fi. Teracopy is on par when copying from a USB 3.0 drive to another USB 3.0 on the same computer.

@Winuser ,

I have no idea why it was not as fast, but I was not copying over ethernet or WiFi. I was copying from an internal HDD to an external HDD via a good-quality USB-C cable.

I am happy with Teracopy Pro. FastCopy was showing the same speed fluctuations as Teracopy Pro and File Explorer, so I saw no reason to keep it. My aim was to find a cause for the speed fluctuations, not to compare Teracopy Pro against FastCopy. I have read that many say FastCopy is better, but a few MB/s is not enough to make me abandon TeraCopy Pro.

Thanks for your reply. Have a great day.

Regards,
Phil

Not to mention Code Sector is working on making TC mutli-threaded, at which point FC won't have near as much of an advantage.

But, that also brings up a good point - if FC is showing the same then it is right back to where we were before, it's a Windows thing, and that means that other versions of TC probably won't help you any.

You're still welcome to try, garioch, but I suspect that other versions will not make a difference whatsoever.

@johnlgalt ,

johnlgalt said:

But, that also brings up a good point - if FC is showing the same then it is right back to where we were before, it's a Windows thing, and that means that other versions of TC probably won't help you any.

You're still welcome to try, garioch, but I suspect that other versions will not make a difference whatsoever.

Click to expand...

I have to agree, John. I usually try to avoid beta releases unless it is concretely suggested that they will solve a particular issue that I am experiencing.

We may never find a reason. It could be that the gremlin in Dell XPS 8930 is really good at hiding. I am not going to put out $4K to get an equivalent desktop to this one just have a smooth copy speed graph! I am a Scot, so I am a bit frugal. After the divorce a few years ago, I am down to half-pension and half-savings, and I never was rich.

Thank again. Have a great day.

Regards,
Phil

garioch7 said:

@johnlgalt ,



I have to agree, John. I usually try to avoid beta releases unless it is concretely suggested that they will solve a particular issue that I am experiencing.

We may never find a reason. It could be that the gremlin in Dell XPS 8930 is really good at hiding. I am not going to put out $4K to get an equivalent desktop to this one just have a smooth copy speed graph! I am a Scot, so I am a bit frugal. After the divorce a few years ago, I am down to half-pension and half-savings, and I never was rich.

Thank again. Have a great day.

Regards,
Phil

Click to expand...

Or it could be Windows lol.

And since Windows is not a Scottish product ...

Then it's crap!

Click to expand...

Lol - I couldn't resist. And well met, btw, My folks are immigrants from India but I was born and raised in the states, or as some over your way say,

Across the pond.

Click to expand...

Cheers!

garioch7 said:

I did install "Fast Copy" to test it, but it was slower than Teracopy, so I uninstalled it.

Click to expand...

FastCopy is portable so, it cannot be installed. You probably got the wrong program, which would immediately help to explain why it was slower.

@hdmi ,

Thank you for your reply. I removed FastCopy from my computer. I only had it briefly. I am sure it was the correct program."Uninstall" was probably not the right word to use. I got it from their website, which does mention an "installer."

I could well be mistaken that it was an "installed" program. I only tried for an hour or so about a month ago and then got rid of it.

Have a great day.

Regards,
Phil

garioch7 said:

@hdmi ,

Thank you for your reply. I removed FastCopy from my computer. I only had it briefly. I am sure it was the correct program."Uninstall" was probably not the right word to use. I got it from their website, which does mention an "installer."

I could well be mistaken that it was an "installed" program. I only tried for an hour or so about a month ago and then got rid of it.

Have a great day.

Regards,
Phil

Click to expand...

Yeah, it can be installed but installing it is entirely optional. Sorry for the confusion. When you click on the Extract button of the installer, the installer behaves like a self-extracting archive letting you pick a folder, in which it will extract its contents. Either way, if it performed slower for you than TeraCopy, then that's definitely not normal. FastCopy does, however, have a whole plethora of options. So, there is a bit of a learning curve.

@hdmi ,

I did not alter any options for my brief testing. Once I saw it was slower, I just removed it.

Multi-threading is coming to Teracopy, so I hear, so I will wait. I have been using Teracopy now for years and know my way around that program.

Thanks for your clarification. Have a great day.

Regards,
Phil

garioch7 said:

@hdmi ,

I did not alter any options for my brief testing. Once I saw it was slower, I just removed it.

Multi-threading is coming to Teracopy, so I hear, so I will wait. I have been using Teracopy now for years and know my way around that program.

Thanks for your clarification. Have a great day.

Regards,
Phil

Click to expand...

I was using Teracopy this morning and it got an update to v. 3.17.

@Winuser ,

Thanks for the heads-up. I was running 3.12. I updated it a few minutes ago to Version 3.17.

I will see on Friday if it solves my peculiar issue.

Have a great day.

Regards,
Phil

garioch7 said:

@Winuser ,

Thanks for the heads-up. I was running 3.12. I updated it a few minutes ago to Version 3.17.

I will see on Friday if it solves my peculiar issue.

Have a great day.

Regards,
Phil

Click to expand...

I truly hope the update helps. I was happy with my Wi-Fi upload speeds until I was told that the speeds should be around the same as copying from one drive to another drive. I could move the Comcast all-n-one router from upstairs to the downstairs but it would be a very major pain in the arse. I did more than double the speed when I upgraded the Wi-Fi 5 card in my old desktop to a Wi-Fi 6 card.

Lol - I was just coming to mention the new upgrade.

Let's see how it works.

@johnlgalt ,

I will know tomorrow afternoon if it makes any difference. I am not really optimistic since I see the same fluctuations with File Explorer when copying, but who knows: the combination of a new version of Teracopy plus the latest preview Windows update might have fixed it.

I will report back tomorrow. Have a great day.

Regards,
Phil

@johnlgalt ,

The updates (Windows and Teracopy) made no difference.

The mystery remains. I did note that the backup programs (Macrium Reflect Version 8 Home and 2023 Easeus Todo Backup Home) have relatively stable image copy speeds, considering that they are backing up and compressing files of various sizes. There was no cyclic pattern like I see when copying my backup images to an external HDD via USB. My OS drive (C:) programs and data are being backed up from a 1 TB Intel NVMe SSD to my new internal 4 TB WD Black drive (G:).

The problem of huge and cyclic copy speed variations occurs only when copying the large backup image file/folder from the target drive of the initial backup (G:) to an external HDD (5 TB WD My Passport Ultra) and to any other external HDD.

Have a great day.

Regards,
Phil

@garioch7 I don't know what happen but for some reason when I now copying from a USB 3.0 HDD to another USB 3.0 HDD the transfer speed is showing less than 100GB/s and when doing a Wi-Fi upload it has increased to just under 30GB/s. If there is an actual slow down it's not noticeable. I'm running the Insider Canary build on the computer and I think an update is causing the computer to not show the true speed. I just wanted to let you know what I'm now experiencing so you know that it could just be a bug when showing the actuall copy speed.