We have a USB drive plugged into an ESX 6.0 host and passed to a Windows VM. The problem we have is the very slow transfer to the drive and/or the transfer freezes for minutes at a time. When looking at Resource Monitor during the transfer, the disk activity and queue length are at 100% and the USB drive becomes unresponsive. When the transfer completes the disk activity drops back to 0% (ish).
A 1GB file gets to 99.9% in a few seconds, then takes 4-5 mins to do the last 40mb. Or sometimes it will do 50% and freeze for a few minutes and then do the other 50% in seconds. Very random.
Copying to the OS drive has no problems so it definitely relates to USB. We have tried 2 different USB drives, 2 different Windows VMs and two different ESX servers from different manufacturers. All of them have this same problem.
I have found an article on VMware forums but there is no answer, however it shows that the problem also occurs on other versions: https://communities.vmware.com/thread/330646
Thanks in advance.