Simultaneous file copy slow on Win 11

carpangler · Sep 23, 2023

If I copy 2 large files using explorer to a USB drive from an NVME drive (Both files on same NVME to same USB drive) they copy at around 35 MB/s each. As soon as 1 finishes the 2nd file increases to around 190MB/s. Does anyone else see this and if so worked out why and how to increase simultaneous copy speeds. I might try robocopy later and see what that does on multiple copies at once.

Ghot · Sep 23, 2023

carpangler said:
If I copy 2 large files using explorer to a USB drive from an NVME drive (Both files on same NVME to same USB drive) they copy at around 35 MB/s each. As soon as 1 finishes the 2nd file increases to around 190MB/s. Does anyone else see this and if so worked out why and how to increase simultaneous copy speeds. I might try robocopy later and see what that does on multiple copies at once.

If you copy the files one at a time, at the same time, this will happen.
Try selecting BOTH files (using the Ctrl key), and then use copy/paste.

In my backup system, I copy two large backups (18GB each), from one hard drive to another.
I select the first file, then hold the Ctrl key and select the other.

Then I right click them and choose Copy. Then, wherever I want them to be... I right click and choose Paste.

Doing it this way.... both files copy at the full hard drive speed of 245 MB/s

This was copying two 18GB files from one hard drive to another(with both selected at the same time)...

iko22 · Sep 23, 2023

carpangler said:
Does anyone else see this and if so worked out why and how to increase simultaneous copy speeds.

The speed difference appears to be five fold when the computer resources are being asked to do four things simultaneously: multi-task two copy processes and parallel read/write two hardware I/O operations. Sounds about right to me, just using rule of the thumb.