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

I am running a Dell 8930 SE, purchased new in October 2019. It has 32 GB DDR4 of RAM, running at 2666 MHz., Windows 11 Pro, with a 1 TB Intel NVMe SSD (C:) and a second 2 TB Seagate HDD (D:). My practice weekly has been to do full system images of all partitions on the C: drive every Friday to the D: drive, alternating between Macrium Reflect Home, Version 8, and Easeus Todo Backup Home. From there, I copy the backup image to a 2019 Western Digital (WD) 4 TB My Passport Ultra (USB-C) to avoid possible problems with losing my D: drive backup image to a malware attack. That WD drive is only plugged in to copy backups and then disconnected and stored in a fireproof safe.

I use Teracopy Pro as my main copy engine. For years, I have been achieving a steady copy speed of 105 MBs, plus or minus 15 MBs. About five weeks ago, my copy speeds, after the first 7 GB of the image file was copied, started fluctuating wildly from 220 MBs to 3.8 MBs, up and down repeatedly. The average copy time is the same: about 24 minutes, but the cause of the copy speed fluctuations is a mystery to me. I also tried using the native Windows copy command from File Explorer, and it, too, had the same wild copy speed fluctuations.

My first suspicion was the WD external drive was failing. I have Hard Disk Sentinel Pro running continuously on my computer, which reported that the WD drive was 100% healthy. I ran the extended test of the WD diagnostic software on the drive. It came back clean.

I have a new 5 TB WD My Passport Ultra drive. I tried it. Same thing: copy speeds of my backup images fluctuated wildly. I then tested with an older 3 TB WD My Passport Ultra drive, and again, the same phenomenon was reproduced.

My next suspect was OS corruption. An SFC scan came back clean. A "DISM . . . /Check Health" scan stated no corruption in the Component Store was detected. A "DISM . . . /ScanHealth" scan reported that "The Component Store is repairable." So I ran the "DISM . . . /RestoreHealth" option, which reported that it had been completed successfully.

I had heard about problems with the "Copy() and Move() functions that were rectified by a recent Windows update. My Windows is fully updated.

I use Bitdefender Total Security and Malwarebytes Premium, with the recommended exclusions in both programs added. I have done so for years without any issues. My next suspect is those kernel-level programs, but I visit both Forums regularly, and I see no reports of this issue.

I have not installed any new programs or made any hardware changes to the computer since well before this problem started.

All of my external USB drives are configured for "Better Performance." I use the "USB Safely Remove" program rather than the native Windows "Eject" app, so I can see what programs might be preventing a safe USB ejection.

I have done research on this problem, but the solutions that I haven't tried involve messing with the Group Policy Editor and altering the Windows default parameters. I am reluctant to do that, in hopes that someone here may be able to solve this mystery for me.

Thank you for reading this long post, but I wanted to save the volunteers here time by itemizing what I have done to try and resolve the problem on my own. I am more accustomed at Bleeping Computer (BC) to giving help, not asking for it. I joined this Forum because it seemed much more active than the Windows 11 Forum at BC. I have not posted there and will not unless this thread is concluded here as unresolved. It is bad "netiquette" to post in multiple Forums.

I look forward to any and all assistance. Thank you, and have a great day.

Regards,
Phil

PS: Thank you for the warm welcome to Eleven Forum. I am really looking forward to learning a lot and helping others here.

Copying files from a computer to another, to a NAS drive or to USB drives can be variable. The source is first read into memory then delivered to the destination. The format, amount of, sizes and types of files are part of the slowness. If using HDDs [Hard Disk Drive] the rotational speed of the disk/s is important, I saw improvement when changing from 5400RPM drives to 7200RPM drives. Defragging hard drives before copying large amounts of data can help in making the read/write heads not having to search for parts of a file.

I had the same problem, so i just ended up doing a "clone". .

A few other things to consider, @garioch7, in addition to Berton's post:

Check to see what other devices you have plugged in via USB, and remove any that you can, to see if it will revert back to the old behavior or not.

If you're using a USB hub, also try directly connecting it to the USB on your machine instead. Also, perhaps try another USB port if you have more than one high speed port.

Finally, double verify that you have the latest drivers from the Dell support site for your machine, particularly USB drivers.

garioch7 said:

From there, I copy the backup image to a 2019 Western Digital (

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May I ask what your reasoning is that you do this. IMO copying an image that has been verified by the backup software as valid just opens the door for possible corruption of that image when it's copied. If you want 2 identical images, making 2 separate images makes more sense to me than copying as it can be done in a lot less time and stress on your systems resources.
I also have a system drive and a data drive. I never include both drives in the same image. By imaging them separately, I have the flexibility of imaging my system drive more often than my data drive if I want (or vice versa if data changes a lot) as well as allowing me to better utilize and manage the storage options I have available. The key is to always make sure you keep more than one image. I keep AT LEAST 4 plus one I call my gold copy that is stored in a safe not located in my house. Another key is to make sure the images one has will restore.

glasskuter said:

May I ask what your reasoning is that you do this.

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The first drive he mentions is another internal drive on the laptop. The copy is made to an external drive, because, in his own words:

garioch7 said:

I copy the backup image to a 2019 Western Digital (WD) 4 TB My Passport Ultra (USB-C) to avoid possible problems with losing my D: drive backup image to a malware attack.

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Making a new image, or 10 new images, that are still in the same location negates having a clean image in case of Malware attacks on the backups themselves unless they are on a physically removable drive.

Thanks @johnlgalt I understand redundancy and the reasons for it. But in that case doesn't it just make more sense to image twice rather than copying?

Depends. Making multiple images has both advantages and drawbacks.

From one perspective, an advantage is that there is less chance of data corruption as you noted. But, from another perspective, there is a possible disadvantage in that, if the backup routines are run overnight, then that drive has to be connected from the moment the operator leaves until they return - meaning that external drive is connected for an extended period of time, also (possibly) negating any benefit to an 'off site' backup. It can be mitigated a bit, in that you have the backup software set to power off the machine, thereby minimizing the possibility of an infection or other data corruption on the external drive, providing as close to a pristine backup as possible.

However, backing up to the internal drive, and then copying it (especially when using a utility like TeraCopy) will help minimize the data corruption, as it checks the resulting copy via hashing, so you're reasonably sure it is data corruption free. The benefit doing it this way is that the external drive is connected literally only for the time it takes to copy the backup image to it, minimizing the chance of malware infection spreading to it in case of an infection.

So, it's a matter of deciding what is more important to you. In this case, it seems as if the OP prioritizes minimizing the time the external drive is connected.

garioch7 said:

My practice weekly has been to do full system images of all partitions on the C: drive every Friday to the D: drive, alternating between Macrium Reflect Home, Version 8, and Easeus Todo Backup Home. From there, I copy the backup image to a 2019 Western Digital (WD) 4 TB My Passport Ultra (USB-C) to avoid possible problems with losing my D: drive backup image to a malware attack. That WD drive is only plugged in to copy backups and then disconnected and stored in a fireproof safe.

I use Teracopy Pro as my main copy engine. For years, I have been achieving a steady copy speed of 105 MBs, plus or minus 15 MBs. About five weeks ago, my copy speeds, after the first 7 GB of the image file was copied, started fluctuating wildly from 220 MBs to 3.8 MBs, up and down repeatedly.

My first suspicion was the WD external drive was failing......

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I promised in reply to your post in the 'welcome to Eleven Forum' thread to add my observations.

My practice is similar to yours, except that I have nine machines to back up. Every Patch Tuesday I finish off by making a Full Macrium Reflect system image of each machine. I have three external HDDs that I store my images on. I keep three images for each machine, this month's and the two previous months. I have two main image drives, one to keep images from 'odd' months, the other for 'even' months. Both drives also have a copy of the latest image, whatever month it is from. The third drive is intended to be my 'off site' copy of all the latest images (when I eventually find somewhere suitable to keep it ). For now I just store it separately from the others.

That's the intended end result, how I get there is quite another matter. A few of the machines have sufficient space for an internal partition to save their image to and then copied to an external drive. For the rest, they save their image to whichever of the three drives is currently not in use. When all backups are completed all my images will be on just one of the three drives, chosen at random.

This is where the marathon copying session starts. Every image will have today's date in its file name, so for each drive in turn I use RoboCopy to copy all files with the name *<today's date>*.* to each of the other drives. While this is progressing I have Task Manager open at the Performance tab so I can watch the transfer speed.

In any transfer there will always be one of the two drives involved that is the limiting factor, maxing out at 100% activity, whether that's writing or reading. Sometimes through the course of copying a large file the source drive and the destination drive take it in turns to be the one holding up the other. In such cases it's interesting to look not just at disk activity, but also the data transfer speed. This can vary by a factor of 2 (or more), for long periods of time it can be 180-200MB/s, then drop for some minutes to 50-90MB/s - but all the time disk activity will be showing 100%.

This leads me to believe that it's a physical limitation of HDD technology that's slowing my data transfer, some parts of a file may be stored on part of the disk platter, or in such a way, that its just more time consuming for the drive's internal controller to read/write that part of the disk. Hence the data rate varies while disk activity remains a constant 100%.

This is further complicated by the fact that these days virtually all external HDDs (and quite a few internal HDDs) use Shingled Magnetic Recording (SMR).

While SMR drives increase capacity for lower cost (because the drives can use fewer platters than a CMR drive at the same capacity), the way they work also comes with a speed penalty. When you copy data to an SMR drive, the drive temporarily stores the data in a special cache area and uses idle time later to organize it into shingled regions on the platter. Long, sustained writes suffer speed penalties because if the cache fills up, each time an SMR drive overwrites part of a previous track, it must read and re-write the "partially covered" underlying data as well. So SMR drives can perform dramatically slower than CMR drives.

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As I read this and the responses it seems no one is adding anything about the copy speed fluctuations. It seems the issue is happening when copying files using an external USB connection. Not familiar with your Dell but do you have a spot to add another HDD to the motherboard SATA connector? If you can add another HDD (internally) you can try to copy the same files to another internal Sata drive and see if that resolves the fluctuations. This might be some kind of USB port/connection/driver issue.

BamaInArk said:

As I read this and the responses it seems no one is adding anything about the copy speed fluctuations. It seems the issue is happening when copying files using an external USB connection. Not familiar with your Dell but do you have a spot to add another HDD to the motherboard SATA connector? If you can add another HDD (internally) you can try to copy the same files to another internal Sata drive and see if that resolves the fluctuations. This might be some kind of USB port/connection/driver issue.

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I had this same problem the other day. . . The exact same problem, and even changing it to a SATA connection didn't help either. That's why I just decided to do a "Clone". . Seemed like the only way to do it. . . The Clone took less time than the regular copy, but I was also copying 2.57TB worth of Movies & TV Show Series

Thank you all for your responses. I do have the latest Dell drivers. I don't use SupportAsssist or Dell Update. I visit the Dell site every Friday before doing my system images to look for driver updates. I do not use USB hubs. The WD 4 TB and 5 TB drives are connected to the front USB-C port; the 3 TB WD My Passport Ultra drive is plugged into a front USB 2/3 port on the Dell 8930 computer. Same issue with both ports. I will try other front USB 2/3 ports and see if the problem is fixed.

I will also try using Robocopy next Friday to see if it can maintain a steady copy speed. I already use a Robocopy batch file to back up my changing data files daily.

There is room for two more additional hard drives in the 8930, but that leaves the copied image from Drive D: accessible to a possible malware attack, which negates my backup strategy. I do have three spare HDDs, so that is not the issue.

I concur that it is might be an issue with the USB ports or drivers. It would very odd for them to suddenly start misbehaving after years of consistently fine performance, . . . unless I got sideswiped by a Windows update. If that were the case, I would expect to be seeing posts from many other users complaining of the issue.

I do sincerely appreciate all of the time and effort of so many to assist me resolve this issue. Thank you all very much.

Have a great day.

Regards,
Phil

garioch7 said:

Thank you all for your responses. I do have the latest Dell drivers. I don't use SupportAsssist or Dell Update. I visit the Dell site every Friday before doing my system images to look for driver updates. I do not use USB hubs. The WD 4 TB and 5 TB drives are connected to the front USB-C port; the 3 TB WD My Passport Ultra drive is plugged into a front USB 2/3 port on the Dell 8930 computer. Same issue with both ports. I will try other front USB 2/3 ports and see if the problem is fixed.

I will also try using Robocopy next Friday to see if it can maintain a steady copy speed. I already use a Robocopy batch file to back up my changing data files daily.

There is room for two more additional hard drives in the 8930, but that leaves the copied image from Drive D: accessible to a possible malware attack, which negates my backup strategy. I do have three spare HDDs, so that is not the issue.

I concur that it is might be an issue with the USB ports or drivers. It would very odd for them to suddenly start misbehaving after years of consistently fine performance, . . . unless I got sideswiped by a Windows update. If that were the case, I would expect to be seeing posts from many other users complaining of the issue.

I do sincerely appreciate all of the time and effort of so many to assist me resolve this issue. Thank you all very much.

Have a great day.

Regards,
Phil

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You could use TeraCopy. . It maintains speeds

garioch7 said:

Thank you all for your responses. I do have the latest Dell drivers. I don't use SupportAsssist or Dell Update. I visit the Dell site every Friday before doing my system images to look for driver updates. I do not use USB hubs. The WD 4 TB and 5 TB drives are connected to the front USB-C port; the 3 TB WD My Passport Ultra drive is plugged into a front USB 2/3 port on the Dell 8930 computer. Same issue with both ports. I will try other front USB 2/3 ports and see if the problem is fixed.

I will also try using Robocopy next Friday to see if it can maintain a steady copy speed. I already use a Robocopy batch file to back up my changing data files daily.

There is room for two more additional hard drives in the 8930, but that leaves the copied image from Drive D: accessible to a possible malware attack, which negates my backup strategy. I do have three spare HDDs, so that is not the issue.

I concur that it is might be an issue with the USB ports or drivers. It would very odd for them to suddenly start misbehaving after years of consistently fine performance, . . . unless I got sideswiped by a Windows update. If that were the case, I would expect to be seeing posts from many other users complaining of the issue.

I do sincerely appreciate all of the time and effort of so many to assist me resolve this issue. Thank you all very much.

Have a great day.

Regards,
Phil

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I suggested using another internal Sata drive as a test only, not necessarily to leave it there. Also with the USB ports you might try the rear ports also. Again not sure how the USB ports on this Dell are connected but depending on motherboard/cpu combinations some USB ports use different hardware via the motherboard.
Since the issue just suddenly started happening you have to question what changed to cause you to notice this? Driver updates? Motherboard chipset drivers? A Microsoft Update?
Another reason to test using a spare Sata connected internal drive is to help determine if this is indeed USB related or not.

May I politely and respectfully request that those trying to help me do not quote my entire posts to avoid wasting server space at ElevenForum?

In my first post, at the beginning of the second paragraph, I did note that I use TeraCopy Pro as my main copy engine, but the same phenomenon occurred when I used the native Windows copy via File Explorer. I know that my first post was verbose, but I was trying to save people the trouble of suggesting troubleshooting steps that I had already done.

If we cannot solve the USB external hard drive copy speed fluctuations in the next few days, then I will indeed go to the trouble of installing one of my spare SATA internal hard drives to confirm or disprove that it is strictly a USB issue. It is also always possible that some software app or driver conflict is the culprit, but which one(s), and how to identify it/them?

As I stated, I have no concrete idea of why this started occurring about five weeks ago, and apparently, I am pretty much alone with this problem, which obviously makes my current particular computer hardware or software configuration suspect. I had no issues with copy speeds since I purchased this Dell computer in October 2019 until five weeks ago, and I did those copies weekly, and always attended, so I know that the copy speeds were stable until very recently.

Thank you all again for your assistance and suggestions. Have a great day.

Regards,
Phil

BamaInArk said:

I suggested using another internal Sata drive as a test only, not necessarily to leave it there. Also with the USB ports you might try the rear ports also. Again not sure how the USB ports on this Dell are connected but depending on motherboard/cpu combinations some USB ports use different hardware via the motherboard.
Since the issue just suddenly started happening you have to question what changed to cause you to notice this? Driver updates? Motherboard chipset drivers? A Microsoft Update?
Another reason to test using a spare Sata connected internal drive is to help determine if this is indeed USB related or not.

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That's one thing I didn't do is try the 3.0 USB on the motherboard.

garioch7 said:

do not quote my entire posts

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Agreed, and quoting an entire post to reply to just one part of it can make a thread very difficult to read. Especially when it's so easy to quote only the part of a post you want to reply to. Just highlight it......

I sometimes see slow copy speeds and then I'll move the USB drive to a different USB 3 port and get much better speeds. I'll then move the drive back to the original port and it will then be just as fast as the other port. Weird. The logical explanation is that there were just other processes running that caused the slowdown, but I was checking the CPU usage closely and don't think that's the reason. Not sure if any of this helps you, but I believe others suggested trying a different USB port and, based on my experience, would also recommend trying that.

garioch7 said:

May I politely and respectfully request that those trying to help me do not quote my entire posts to avoid wasting server space at ElevenForum?

In my first post, at the beginning of the second paragraph, I did note that I use TeraCopy Pro as my main copy engine, but the same phenomenon occurred when I used the native Windows copy via File Explorer. I know that my first post was verbose, but I was trying to save people the trouble of suggesting troubleshooting steps that I had already done.

If we cannot solve the USB external hard drive copy speed fluctuations in the next few days, then I will indeed go to the trouble of installing one of my spare SATA internal hard drives to confirm or disprove that it is strictly a USB issue. It is also always possible that some software app or driver conflict is the culprit, but which one(s), and how to identify it/them?

As I stated, I have no concrete idea of why this started occurring about five weeks ago, and apparently, I am pretty much alone with this problem, which obviously makes my current particular computer hardware or software configuration suspect. I had no issues with copy speeds since I purchased this Dell computer in October 2019 until five weeks ago, and I did those copies weekly, and always attended, so I know that the copy speeds were stable until very recently.

Thank you all again for your assistance and suggestions. Have a great day.

Regards,
Phil

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Quoting doesn't really take up that much room on the server. It's KBs. Not MB or GB. . Just small KB. An image file is bigger than a quoted post

Thank you all for your replies. I will continue to investigate. Have a great day.

Regards,
Phil