Question SD card read-speed slows down when there's only one card is left to read ?

[Johnmcf2]

I record events using multiple camera and devices that use 250GB SD cards for storage. All cards read at above 95MB/s which is the slowest one. The fastest is 200MB/s. I can only get the computer to recognize 3 readers at a time. Using Windows 10 Home and pro and Windows 11 Home and pro and on two different computers.

The problem goes like this; I stick 3 SD cards in the readers and start downloading them to a 16TB storage disk. Each SD card reads above 60MB/s (total 180MB/s which matches the destination drive speed) and when one finishes, the remaining two go up to 90MB/sec each. Which is great, it is working as expected... until one more SD Card finishes. With one SD Card left the read speed drops to 30MB/sec. It does this no matter which SD card happens to be the last one. For some reason two or more read normal, but a single reads at 30MB/sec.

It looks like a software issue. I have tried many readers and get the same results. Just bought a new computer and still get the same results on both computers with one running Windows 10pro and one running windows 11pro. Also, just putting one SD Card in starts at 30MB/s but speeds up to 90MB/s when one more SD card is started then down to 60 when the third one is started. The issue is only when one SD card is being read.

I am wondering if it is some setting that makes two or more reader activity a higher priority and only one reader active a lower priority... You know... making more room for advertising and information gathering. Of all the post I have seen state the obvious; But this is not normal. 3 SD cards reading (180MB/s total) are each 2x faster then a single reader uploading @ 30MB/s to storage that should be uploading @ 180MB/s.

Any one having a solution would be greatly appreciated.

 

[helpstar]

try a different copy tool

eventually the speed is not accurate and incorrect
check the speed in task manager as well

are you using USB 3.2 or less? Which readers are you using?
in general, pictures usually take more time than videos

usb and chipset drivers up to date?

 

[Johnmcf2]

try a different copy tool

eventually the speed is not accurate and incorrect
check the speed in task manager as well

are you using USB 3.2 or less? Which readers are you using?
in general, pictures usually take more time than videos

usb and chipset drivers up to date?

I use file explorer and have verified that the transfer speed does go down to 30MB/s using task manager. it is so obvious you can use a clock to measure it. The files from each camera only very a few MB and usually run 60GB or more. 4K video for 1.5 to2 hours on 5 cameras. I really am not interested in looking for a third party work around as there are hundreds mixed in with thousands of scams. I have been down that road more times than I would like and learned from those mistakes. Many people have the problem from what I have read but no one has hit the mark on why and have a fix.

My new computer handled it well then suddenly started doing the same thing. Both my computers are AMD Ryzen 7 2700 eight core 3.2GHz Gaming computers with 32GB ram. The only restriction is the 16TB Elements usb drive. when going into internal sata SSD the speads are much faster except when transfering only one file. Something in the software is limiting the speed outside of physical limitations.

For some background I have build High End computers for customers until I went into the industrial Robotics field for the last 30 some years. I just dont have the time to fix microsoft windows issues especially when they dont want it fixed. I prefer to let people that enjoy the challenge to have a crack at it.

 

[Johnmcf2]

I record events using multiple camera and devices that use 250GB SD cards for storage. All cards read at above 95MB/s which is the slowest one. The fastest is 200MB/s. I can only get the computer to recognize 3 readers at a time. Using Windows 10 Home and pro and Windows 11 Home and pro and on two different computers.

The problem goes like this; I stick 3 SD cards in the readers and start downloading them to a 16TB storage disk. Each SD card reads above 60MB/s (total 180MB/s which matches the destination drive speed) and when one finishes, the remaining two go up to 90MB/sec each. Which is great, it is working as expected... until one more SD Card finishes. With one SD Card left the read speed drops to 30MB/sec. It does this no matter which SD card happens to be the last one. For some reason two or more read normal, but a single reads at 30MB/sec.

It looks like a software issue. I have tried many readers and get the same results. Just bought a new computer and still get the same results on both computers with one running Windows 10pro and one running windows 11pro. Also, just putting one SD Card in starts at 30MB/s but speeds up to 90MB/s when one more SD card is started then down to 60 when the third one is started. The issue is only when one SD card is being read.

I am wondering if it is some setting that makes two or more reader activity a higher priority and only one reader active a lower priority... You know... making more room for advertising and information gathering. Of all the post I have seen state the obvious; But this is not normal. 3 SD cards reading (180MB/s total) are each 2x faster then a single reader uploading @ 30MB/s to storage that should be uploading @ 180MB/s.

Any one having a solution would be greatly appreciated.

I am going to try something new based on what people said about microsoft limiting the USB endpoints. I ordered 6 SD USB dual readers that can be plugged into a 7 port USB hub lowering the endpoint count by than half. I am currently using UGreen 4port readers each reader can only read one of my type SD Card but opens a port for each of the different types of cards it can read. Having 3 UGreen readers opens up 12 ports alone and then the Elements USB drive takes one, my two printers each take one, and the mouse and keyboard. That is 17 endpoints which may exceed the limit of 10 people say they implemented. May not even apply to this scenario but I would like to be able to plug all 5 SDCards in and walk away during the transfer. For some reason plugging in 4 or more disables one such that only 3 are recognised at a time even though they all show up in the tree.

 

[helpstar]

file explorer from Microsoft or a different one?

 

[Ralston18]

Take a look at what is happening (or maybe not happening) as you go through the cards.

Use Task Manager, Resource Monitor, Performance Monitor, and Process Explorer (Microsoft, free) to observe system performance. (All are Microsoft and not third party.)

Use all of the tools but only one tool at a time.

Leave the tool window open and simply watch what happens.

Good chance that you will be able to spot what, when, where, etc. the downloads begin to falter.

Task Manager and Resource Monitor are good starting points.

Process Explorer:

https://learn.microsoft.com/en-us/sysinternals/downloads/process-explorer

Performance Monitor - requires much more effort and time. Try the other tools first.

 

[Johnmcf2]

file explorer from Microsoft or a different one?

It is Microsoft Windows file explorer that comes with windows. One computer is running windows 10 and the other is running windows 11. Both have recently been upgraded to Pro for group policy functionality. File explorer stays pretty much the same. My laptop which is also running the same AMD Ryzen 7 CPU has a newer version for laptops that looks like it was developed for the kindergarten students. Gets a "F" for all catagiries. Glad I dont use it much for file management. pretty colors but have to figure out yet if it does anything. Guess we all be on the same playing field. We all get to learn all over again... How many 70 year olds ever wanted to go back to Kindergarten and start over? Well; You got your wish.

 

[Johnmcf2]

Take a look at what is happening (or maybe not happening) as you go through the cards.

Use Task Manager, Resource Monitor, Performance Monitor, and Process Explorer (Microsoft, free) to observe system performance. (All are Microsoft and not third party.)

Use all of the tools but only one tool at a time.

Leave the tool window open and simply watch what happens.

Good chance that you will be able to spot what, when, where, etc. the downloads begin to falter.

Task Manager and Resource Monitor are good starting points.

Process Explorer:

https://learn.microsoft.com/en-us/sysinternals/downloads/process-explorer

Performance Monitor - requires much more effort and time. Try the other tools first.

Been doing that for years. That is why I see it as a built in limit for some reason that just is not about the business of transferring files as fast as possible. It would be nice if Microsoft would address the issue and not try to explain the basic functions of file transfer. Been out if college for over 40 years... even taught college basic computer skills... so let's all get back to the problem of why two SD cards upload at 90MB/s and drops to 30MB/s if one finishes. I take some time to rename the files on theSD cards before I start uploading each one and this makes a lag in start times an due to only being able to do 3 at a time ends up with the last card uploading at 30MB/s for 5 minutes or more. If I plug in another SD card it speeds back up to 90MB/sec each or 180MB/s total. I would reduce the time alot by just doing exactly that and then stop the dummy load when the last card is finished. Bandaids on broken bones...

 

[Ralston18]

Always just a matter of only the last SD becoming slow - correct?

No apparent dependencies on any given SD card, card reader, cables or USB port(s) or combinations thereof?

I think Process Explorer may prove helpful.

Just watch what happens/changes when uploading and/plugging in SD cards.

= = = =

What system resource changes in any manner when performance slows?

Task Manager > Performance likely to change in some manner. Check the other Task Manager options as well - e.g. Processes.

Graphical Views make make any changes more apparent.

= = = =

There may be an additional way to obtain more information - have you worked with Powershell at all?

Very powerful and useful.

For examaple:

Get-PNPDevice -Class USB
Reference:

https://powershellfaqs.com/list-usb-devices-using-powershell/

Not a direct answer about "Why?" with respect to the speed events being observed.

However, you may note some other unexpected or unknown bit of information that could help identify the reason(s).

That said I looked into something else I was wondering about and came across the following link:

https://learn.microsoft.com/en-us/windows-hardware/drivers/usbcon/usb-bandwidth-allocation

From the link, Paragraph 4:

"Occasionally, a client driver exhausts the available bandwidth with a high-speed interrupt transfer. But the most common case, by far, is that of a client driver that allocates too much bandwidth for an isochronous transfer, then fails to release the bandwidth in a timely fashion."
My underlines.

That is about as close to an explanation as I have found thus far with respect to the cited problems.

The paragraph seems to match what is happening.... transfers slow until your actions release the bandwidth again.

Which makes me think that one solution may be a simple script that emulates what you do to get the speed back up again.

Out of my comfort zone a bit (full disclosure) but no harm in thinking about it.

Powershell can also provide some information about USB bandwidth allocation.

Something that I have not worked with but will do some testing and experimenting as warranted.

 

[helpstar]

maybe try :

View: https://www.youtube.com/watch?v=1kSXOYXexMI

 

[Johnmcf2]

Always just a matter of only the last SD becoming slow - correct?

No apparent dependencies on any given SD card, card reader, cables or USB port(s) or combinations thereof?

I think Process Explorer may prove helpful.

Just watch what happens/changes when uploading and/plugging in SD cards.

= = = =

What system resource changes in any manner when performance slows?

Task Manager > Performance likely to change in some manner. Check the other Task Manager options as well - e.g. Processes.

Graphical Views make make any changes more apparent.

= = = =

There may be an additional way to obtain more information - have you worked with Powershell at all?

Very powerful and useful.

For examaple:

Get-PNPDevice -Class USB
Reference:

https://powershellfaqs.com/list-usb-devices-using-powershell/

Not a direct answer about "Why?" with respect to the speed events being observed.

However, you may note some other unexpected or unknown bit of information that could help identify the reason(s).

That said I looked into something else I was wondering about and came across the following link:

https://learn.microsoft.com/en-us/windows-hardware/drivers/usbcon/usb-bandwidth-allocation

From the link, Paragraph 4:

"Occasionally, a client driver exhausts the available bandwidth with a high-speed interrupt transfer. But the most common case, by far, is that of a client driver that allocates too much bandwidth for an isochronous transfer, then fails to release the bandwidth in a timely fashion."
My underlines.

That is about as close to an explanation as I have found thus far with respect to the cited problems.

The paragraph seems to match what is happening.... transfers slow until your actions release the bandwidth again.

Which makes me think that one solution may be a simple script that emulates what you do to get the speed back up again.

Out of my comfort zone a bit (full disclosure) but no harm in thinking about it.

Powershell can also provide some information about USB bandwidth allocation.

Something that I have not worked with but will do some testing and experimenting as warranted.

I have been at it for awhile. The card readers came in and I plugged them all into a 7 port usb3.0 hub and.... failed, three worked 2 failed to initialize... and continuously tries giving notifications each time it tries and each time it fails about every 2 seconds.

Played with them and got 3 to work on one hub, two to work on another hub but one was the USB hard drive, and the last I plugged into a SSusb port no hub. took a few tries but it settled down and transfered all 5 SD Cards into a USB Ekements 2TB drive each going around 9MB/sec (total 45MB/s). So this Highspeed gaming computer has limitations. Low speeds are consistant also with a slow USB interface bottle neck to the destination drive an older Elements Hard drive.

All said and done the speeds looked consustant while I was watching; but at those speeds the time was estimated at 1 hour. This was done on my new Windows 11pro system. have to play around some more. Looks like just running three at a time @ 60MB/s or two at a time at 90MB/s are better than trying to read all five at once @9MB/s. Plus totally unreliable. Locked up my whole computer a few times. have to try to duplicate what ever I did on the windows 10 Pro computer. Still no solution to what is causing the speed drop instead of rise when the last one is finishing.

 

[Ralston18]

Hubs: Powered via host system USB or or independently powered?

Is it possible for you to sketch out a simple diagram showing the hardware setup and connections?

Make, models, ports, etc..

Nothing fancy: just enough to provide the "big picture" view of how it all is set up.

Then scan or photograph your diagram and post that here via imgur (www.imgur.com > green "New post" icon".

Someone may spot something amiss.

Also:

"Locked up my whole computer a few times."

Check Reliability History/Monitor and Event Viewer for any error codes, etc. captured just before or at the times of those lockups. Look at the technical details - may or may not be helpful.