# Thunderbolt 2 vs. USB 3



## ptram (Sep 30, 2021)

Hi,

I've my sample library SSDs connected to one of the USB 3 ports of my Mac Pro 2013. Four of them are in a bay connected to a single USB port, and another one to another USB port.

I've three Thunderbolt connectors free, so I wonder if using one of them with a Thunderbolt 2 to USB 3 adapter/hub would work better. I will for sure make the USB bus lighter. But will I also get higher speed from my sample SSDs?

Thank you for your hints.

Paolo


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## Al Maurice (Sep 30, 2021)

Hi Paolo -- it really depends on the throughput of your drive and your MAC.

And what generation of USB 3 you have, as the bandwidth varies.


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## easyrider (Sep 30, 2021)

Thunderbolt 2 has a transfer speed of 20 GB per second. Thunderbolt 1 has a transfer speed of 10 GB per second and USB 3 has a transfer speed of 5 GB per second.

Some more info here

https://www.apple.com/uk/thunderbolt/

Your bottleneck will always be the slowest device...

Change your HUB to a TB 2 and it would significantly improve speeds and bandwidth.


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## ptram (Sep 30, 2021)

Al Maurice said:


> it really depends on the throughput of your drive and your MAC. And what generation of USB 3 you have, as the bandwidth varies.


It looks like the 4-drive bay is USB 3.0. The Mac's Thunderbolt ports are generation 2.



easyrider said:


> Your bottleneck will always be the slowest device...
> Change your HUB to a TB 2 and it would significantly improve speeds and bandwidth.


So, with SSD drives and a Thunderbolt 2 interface in the computer, the bottleneck is, as expected, the USB 3.0 port in the bay. I should expect a TB-USB to change nothing.

It's hard to find TB2 bays, so it would probably be better I find a TB3 bay, and a TB2-3 adapter. The bay will be safe for the next computer. At the moment, I'll be able to run at TB2 speed, that is still a lot better than USB3.

Paolo


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## easyrider (Sep 30, 2021)

ptram said:


> It's hard to find TB2 bays, so it would probably be better I find a TB3 bay, and a TB2-3 adapter. The bay will be safe for the next computer. At the moment, I'll be able to run at TB2 speed, that is still a lot better than USB3.
> 
> Paolo


Yes....TB3 bay using a TB 2 adaptor will be the best solution in your case. Or Get two TB 3 bays and use two TB 2 ports to improve bandwidth and IO.

How Big are the SSD's?

It might worth consolidating them ,depending on size, into a couple of NVME drives.....in TB 2 Enclosures.


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## ptram (Sep 30, 2021)

easyrider said:


> How Big are the SSD's? It might worth consolidating them ,depending on size, into a couple of NVME drives.....in TB 2 Enclosures.


I'm using two 2TB, two 1TB and one 500GB drives. Not totally ready to trash them out, considering how much they did cost!

(I'm all against technological waste – in particular, if it costs me money!)

Paolo


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## easyrider (Sep 30, 2021)

ptram said:


> I'm using two 2TB, two 1TB and one 500GB drives. Not totally ready to trash them out, considering how much they did cost!
> 
> (I'm all against technological wast – in particular, if it costs me money!)
> 
> Paolo



Sell them….put the money towards a couple of Nvme….just one scenario….


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## jbuhler (Sep 30, 2021)

ptram said:


> It looks like the 4-drive bay is USB 3.0. The Mac's Thunderbolt ports are generation 2.
> 
> 
> So, with SSD drives and a Thunderbolt 2 interface in the computer, the bottleneck is, as expected, the USB 3.0 port in the bay. I should expect a TB-USB to change nothing.
> ...


I had good luck with the tb3>TB2 connector for both bays and docks, before I got a computer with TB3/USB-C ports.


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## ptram (Sep 30, 2021)

After looking at the prices of the bays, adapters, cables in the TB3 world, I've decided to continue working with what I have for still some times. All considered, with a more or less constant set of instruments used in VEPro, having to wait a few minutes for the first loading can be tolerable…

Paolo


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## Al Maurice (Sep 30, 2021)

To be honest as a serial protocol, USB is only capable of going as fast as the slowest device on the bus; although you can probably place more devices down one thunderbolt port than the equivalent USB.

Hence I found it's best to put an SSD drive on its own dedicated bus, which worked out best in the end for me.


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