LaCie 5TB external drive not connecting via Thunderbolt

[ursulahx]

I have a 2019 27" Retina iMac (ie the latest model), which has two Thunderbolt ports. I just bought a 5TB LaCie portable external drive from the Apple Store. It comes with a USB-C to USB-C cable. When I connect the drive to the Thunderbolt port, it does not appear on the desktop. All the connections are firm and secure. The drive also has a USB-C to USB-A cable, and when I connect with this (via one of the four USB ports on the iMac), the drive appears.

Now I know USB-C and Thunderbolt are not identical, but my understanding was that USB-C will connect successfully with a Thunderbolt port (especially a recent one). What am I missing?

The drive appears to function successfully in all other respects.

(By the way, the drive features in the Apple Store when I filter by 'Connection - Thunderbolt 3'.)

 

[jaytv111]

Do your Thunderbolt ports work with other devices? Does the cable work? Could you test out different cables and different ports (ie, if you were plugging into only one TB3 port test out the other one). Sounds like something went bad between the two. I have a USB-C SSD from Lacie and a Macbook Pro with Thunderbolt 3 and it works perfectly fine with the TB3 ports. Thunderbolt 3 switches automatically to USB protocol so it should have no problem with this drive. Also try out an adapter from type-C to female USB-A in the TB3 ports. That will tell you if this specific port works even if through an adapter with this specific drive.

Also, does the drive show up at all in the System properties, under USB?

 

[ursulahx]

Thanks for the response. I don't know if the TB ports work, as this is the first device I've plugged into them. I suppose it's possible they don't, although it would be very disappointing for Apple to sell a brand new iMac with two defunct TB ports. Not impossible, I guess. (Yes, I've tried both ports.)

It could be the cable that's the problem but it's the only USB-C to USB-C cable I have, and a new one costs more than I really want to spend.

The drive does show up under USB - it's currently connected to one of the USB ports, as I'm transferring a hefty amount of data. I was hoping the transfer would be quicker with TB which is why I bought the drive...

Good idea about the adapter, I've got one somewhere. I'll give it a try and report back.

Thanks again.

 

[jaytv111]

If both ports are failing to work then it could be the controller, there's one thunderbolt controller behind the two ports (Macbook Pro 15" like mine have 2 controllers, one on each side of ports).

Or the cable was defective.

Ports and controller and cable seems to be the only things tying everything together. You probably should buy a USB-C to C cable. If it works with a different cable, then great, everything is okay except for a defective cable that came with the Lacie. If it still does not work, then the TB ports/controller/something or other between them is broken. One thing to note, you should make sure it's a 3.0/3.1 gen 2/Superspeed 10 Gbps cable. There are cheaper 2.0 cables that will slow you down considerably.

The drive will not be faster with USB-C or Thunderbolt. It's only a hard drive which transfers up to 130 MB/s according to the Lacie site. In my experience, USB 3.0/3.1 gen 1 is good for up to about 400-450 MB/s (I've had different SSDs and HDDs over the years). Gen 2 USB can handle about 1 GB/s and Thunderbolt 3 about 2.8 GB/s (you need good NVMe SSDs to take full advantage of Thunderbolt).

130 MB/s is way lower than the USB-A ports can go to. If you had an SSD it would be a different situation, where 10 Gbps USB or 40 Gbps Thunderbolt 3 would help a lot. But otherwise you're good with using USB-A, it will absolutely not slow down the drive. My Lacie is an SSD with 10 Gbps USB and it does slow down if you use 5 Gbps USB, and waaaaaay slows down with 2.0 USB.

 

[ursulahx]

Thanks for setting me straight on that last point. I tested with an adapter (connecting the drive with the USB-C -> USB-A cable into the USB-C port via an adapter) and it works. So the good news is I've freed up a USB port, which was one of my other objectives.

(Ironically, buying two adapters on the Apple Store is cheaper than buying Apple's own brand USB-C cable.)