Slows 235MB's - Copying from external usb3.1 NVMe SSD to internal cache drive also NVMe (gen4)


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Copying from usb3 external NVMe ssd to cache drive NVMe so why is it so slow?


Is there a problem with speed if you use a cache pool mirror?

I have 1x gen4 NVMe & 1x gen3 NVMe on the motherboard as a cache pool - so the gen4 is mirrored to the gen3.


When I use diskspeed test docker both SSD drives are around 2300MB/s.


It shouldn't be touching the array disks. The share is set to use Cache. But anyway I am copying direct to cache rather than the user share.


The array drives test around 240MB/s down to 108MB/s.



My understanding is USB 3 provides up to 500MB/s read & write. ( Dependent upon encoding overhead )


And USB 3.1 up to 1200 MB/s read & write. ( Dependent upon encoding overhead )


Screenshot 2022-09-22 at 15.12.38.png

Edited by dopeytree
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