For a project i had to move quite a lot of data, which is used as an initial seed for replication, to a second location. The best device i could find quickly was a 1TB USB disk. OK, fine…
Copied all the data to the disk on my client and shipped the disk to the second location. There it was attached to a vSphere host directly. Never used USB device on a vSphere host directly before, but knew that it works.
So i added a “EHCI+UHCI” controller to the VM and attached the USB disk. Fine… Well… Not that fine. A transfer rate of 5-6MB/s isn’t fine at all. Even for a cheap USB disk.
Stopped the copy process, removed the device and controller from the VM and added an xHCI controller instead of the “EHCI+UHCI”. And now, 30MB/s. Much better!
Conclusion:
Always use a xHCI USB controller if you have to attach a USB device to a VM which needs performance.