Setup and Theory
I'm testing my USB connection from my Laptop to an external USB 3.0 drive and vice versa by copying a ~3 Gigabyte folder back and forth. Natively my laptop does only have USB 2.0 ports (up to 480 Mbit/s), so I bought an adapter to plug into its Thunderbolt 1 port and get USB 3.0 that way.
In theory this should work: USB 3.0 can provide up to 5000 Mbit/s and Thunderbolt 1 up to 10'000 Mbit/s (on each of the two channels). So the setup laptop - adapter - hard drive should get my USB 3.0 speeds, I think...
Laptop ------> Adapter ------> External Hard Drive | | Thunderbolt 1 USB 3.0
Actual Copy times
My experience differs though! The measured times to copy that ~3 Gigabyte folder are as follows:
- External hard drive to Laptop 24 seconds.
- Laptop to External hard drive 45 seconds.
I therfore calculate bitrates of 980 resp. 520 Mbit/s, which is roughly 20 resp. 10 % of the maximal bitrate of USB 3.0. If I plug a docking station to this adapter and connect hard drive to it and, in addition, an external screen, the transmission times go up, i.e. bitrates plummet (also, the screen is laggy):
- Both directions 77 seconds - so approx. 307 Mbit/s.
DVI Laptop ------> Adapter ------> Docking Station ------> Screen | | ------> Ext. Hard Drive Thunderbolt 1 USB 3.0 | USB 3.0
Of course this is way faster than USB 2.0, when I connect the external hard drive directly to the laptop:
- External hard drive to Laptop 86 seconds.
- Laptop to External hard drive 117 seconds.
So that's about 270 Mbit/s resp. 200 Mbit/s, or about 60 resp. 40 % of the max. speed of USB 2.0.
Laptop -----> External Hard Drive | USB 2.0
Is my assumption, that I should get USB 3.0 speeds with the setup
Laptop - Thunderbolt 1 > Adapter - USB 3.0 > Device, true?
Are these USB 3.0 transmission speeds normal?
Are these USB 2.0 transmission speeds normal?
If no once or twice: Why? Which device is responsible for these results?