Windows 10 file write performance

I was recently following the excellent tutorials on using Macrium Reflect free. I successfully created a clean windows install (using yet another excellent tutorial), updated all drivers, installed all patches and applications.
I then used the Macrium boot USB to start my desktop and created an image of this perfect install to an external HDD. The process worked without a hitch.
However I have noticed something peculiar, under the Macrium boot OS, the write speed of the external HDD is quoted as 503Mbs (365Mbs was the slowest write speed). My entire 33Gb install was imaged in just under 11 minutes.
Once back in Windows I decided to copy the image I had made to another partition as a backup, Windows reports the write speed of the external HDD as 20Mbs max, and quite often well below 8Mbs. The copy operation took well over half an hour.
So why the difference? Is the overhead for Windows 10 really that bad? And what if anything can I do to improve the performance?

But that's the point, I was copying 1 file of 33Gb size, not multiple files of various sizes.
The write performance under Macriums OS was average 503Mbs to the external HDD, in Windows the write performance on the same HDD was 20Mbs with an average of 8Mbs using the same 33Gb file.

Macrium Reflect uses compressed data thus the write speeds shown. Try doing a backup image with compression off to see the difference. Also, an active antivirus (Windows Defender or others) may impair write performance.

thomaseg1 said:

Is the usb drive set to best performance in device manager?
That can have an effect on speed.

Hi Thomas, do you set your USB device to best performance, and if you do, have you ever experienced data loss or corruption of the USB device?

Thomas, I've had my pc for 4 of 5 years. I've used USB's many, many, many times. But I never knew the USB icon existed. It only pops up is when you have a USB inserted. I have my taskbar hidden and when I have a USB inserted, the icon is also hidden. Learn something everyday.

Pejole2165 said:

I was recently following the excellent tutorials on using Macrium Reflect free. I successfully created a clean windows install (using yet another excellent tutorial), updated all drivers, installed all patches and applications.
I then used the Macrium boot USB to start my desktop and created an image of this perfect install to an external HDD. The process worked without a hitch.
However I have noticed something peculiar, under the Macrium boot OS, the write speed of the external HDD is quoted as 503Mbs (365Mbs was the slowest write speed). My entire 33Gb install was imaged in just under 11 minutes.
Once back in Windows I decided to copy the image I had made to another partition as a backup, Windows reports the write speed of the external HDD as 20Mbs max, and quite often well below 8Mbs. The copy operation took well over half an hour.
So why the difference? Is the overhead for Windows 10 really that bad? And what if anything can I do to improve the performance?

Macrium use's when the device is capable, Direct I/O. Extremely fast as you noted. The I/O method used by Windows is generic. Its not tailored to any one device. When I image (Full) my system disk only (its 50gb on a SSD) and the target disk is a SSD (Output size is around 33gb), the job elapsed time is 3:30 on the average. Smoking fast.


Macrium is the Best imaging tool I have ever used.

Oh I don't disagree about Macrium, it is a wonderful piece of software. I did try an image with no compression, you were of course right, write speed was almost exactly half 263MBs using Macrium "DOS" disk. Guess I really need to embrace the world of SSD's.
And in answer to an above post (sorry for delay) yes I use performance setting on external drives/ thumb drives.
Understanding the way it works I see the reason for the difference now.