Is it possible to attach more than one USB 3.0 external HDD to a powered USB 3.0 hub?

I have a mixed USB 3.0/2.0 hub (4 ports USB 3.0, 3 Ports USB 2.0 and one port for charging USB devices). One of the USB 3.0 ports is connected to a 4 TB Seagate external USB 3.0 HDD.

I tried to attach a 2nd USB 3.0 external HDD (Seagate 3 TB). Windows 10 can see the second drive, I can assign it a letter, I can navigate its structure, I can create new folders and new text documents. However, when I try to copy any file to it, Windows Explorer gets stuck at Calculating....

I have only one USB 3.0 on my laptop, so I don't know what would happen if I connect the 2nd USB 3.0 HDD to another USB 3.0 port. When I connect it to a USB 2.0 port, everything is fine. Also, if I connect the 2nd drive to the USB 3.0 port on the router, it works fine (it becomes a slow speed NAS).

So, I'd like to ask the experts, is it possible at all to have two or more USB 3.0 HDDs connected to a USB 3.0 hub and have them all work?
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  1. that really all depends on the hub in question. The USB spec calls for USB to be able to daisy-chain 127 devices to a single port.
    in theory you should be able to plug a hub into each of the ports on the hub and quickly have many many devices off the single port.
    not all hubs are created equally or even properly. older hubs shared a single transaction translator which would slow everything on the hub to the slowest device connected.
    I doubt this is the issue.
    I have three USB 3.0 drive's, 1TB, 4TB, 32GB connected to a hub on a single USB 3.0 port.
    yes it does/can/should work
  2. You use the phrase "powered USB3 Hub", but do not give any details of how the Hub is "powered". And I must admit I have seen confusing (misleading?) labels on Hubs for sale.

    Any USB port must be able to provide power to something plugged into it, but there are limits. And where does that power come from? Well, the simplest Hubs are called "USB Bus Powered", which means that the Hub's ONLY source of power is the one USB port it is connected to. Thus its limit is that the TOTAL power it can supply to ALL its devices is what comes out of only one host port. Personally, I prefer to call such Hubs "Unpowered", and I reserve the term "powered USB Hub" for one that has it own "power brick" that plugs into the wall and provides to the Hub enough power for ALL its ports at full load. Plus, of course, you actually have to use that power brick when you use the Hub.

    Now, USB2 had a limit of 0.5 amps at 5 VDC for EACH port. USB3 raised that to 0.9 amps per port. But here's one spot that can cause confusion: it appears many powered USB3 hubs come with a power brick that supplies 12 VDC to the Hub, and then the Hub changes that to 5 VDC for its attached devices. So we have to start looking at the specs in WATTS. The USB3 power to EACH port is 4.5 Watts, so the power brick for a Hub must be able to provide at least that PER Port. For example, a 4-port USB3 Hub should have a power brick able to provide 18 - preferably 20 - WATTS to the Hub. A Hub like yours, OP, should be getting at least 20W for its four USB3 ports, plus 8 W for its three USB2 ports, plus 10 W (2 amps at 5 VDC) for the charging port from its power brick. That's nearly 40 W. Now, I know that some such Hubs come with a power brick a little less capable than that because it saves money and they estimate that the Hub will never actually be used with all its ports using max power simultaneously. But that's what you need for what I call a "Powered USB3 Hub".

    So, OP, does your Hub have a power brick it came with? Are you using it? If not, then that Hub can supply to ALL of its connected devices in TOTAL, no more than the 0.9 amps at 5 VDC that comes from the computer's USB3 port that you plug it into. These days, the "portable laptop hard drives" being sold for USB3 systems NEED almost that full power for ONE drive. If you do NOT use a power brick with your Hub, then it can only power ONE such portable drive at a time. BUT if you use the power brick that came with it (I HOPE!), it should be able to power one drive on EACH of its ports with no trouble.
  3. By powered hub I mean a hub which comes with its own power supply and I do use that power supply. I have a USB keyboard, USB mouse, USB laser printer/scanner connected to the three USB 2.0 ports. I have an Ethernet to USB 3.0 adapter, an USB 3.0 4TB external hard disk and a USB 2.0 headset connected to three of the four USB 3.0 ports.

    I forgot to mention in my original post, the 4 TB external hard disk is seen by Windows as MBR, although MBR cannot handle (as far as I know), more than 2 TB. This is a Seagate external USB 3.0 drive. I assume there is some Seagate software which presents the drive as MBR to Windows and any disk utilities (like MiniTool Partition Wizard, which I use).
    I also have a portable (2.5 size, USB bus powered) USB 3.0 500 GB HDD which is also MBR. If I connect this drive to the fourth USB 3.0 port on the hub, the 4 TB and 500 GB HDDs work fine, for reading, writing and navigating.

    The 3 TB Seagate HDD I mentioned in my first post was an internal HDD, which I placed in an USB 3.0 enclosure, purchased separately. Because it is larger than the maximum size allowed by MBR, I've partitioned it as GPT (only one volume for all 2.73 TBytes). It needs an UEFI computer to be accessed, but my laptop has UEFI firmware and its internal hard disk is also partitioned GPT by the manufacturer. If I connect this drive by itself to the USB 3.0 hub, it works fine. If I connect it while the 4 TB or 500 GB is also connected it works as described in my first post (it gets stuck in Windows Explorer on Calculating when copying to it).

    I wonder if this MBR/GPT pairing is what causes the problem, or there is something wrong with the lone USB 3.0 port on the laptop, or something else?

    Many thanks to the two respondents.
  4. By the way, just for clarification, to use a drive partitioned in the GPT system just for DATA, you don't need UEFI Support in BIOS. But you DO need an OS with a driver for such a device, and among Windows OS's, only the 64-bit versions come with such a driver. So you must be running 64-bit Windows to access a GPT disk unless you have some other device driver installed. HOWEVER, it you want to BOOT from a GPT disk, then you MUST have UEFI support in BIOS. That's because the BIOS boot code must be able to read and use the GPT Partition Table to start accessing the disk and find the OS to boot from.

    Now, back to your problem. The new info I note is that the HDD in question is NOT one designed for use as an external or internal on a laptop. It is actually one designed for use as an internal HDD in a desktop machine. Now, laptop drives are specifically designed in several ways to minimize their use of power, and that is how they can run on 5 VDC with less than 0.9 amps. But almost all desktop drives use much more power than that. A quick check of the Seagate site for current Barracuda drives shows that they typically need 2.0 amps to start up, and consume from 5.6 to 8.0 Watts in normal operation. I don't know exactly which model you have or its exact power use, but those typical numbers are MUCH more than a USB3 port can deliver.

    What about the external enclosure you used to house this drive? Does it come with (or can you get additionally) a power brick to provide power to the HDD inside without relying on the USB3 port? For example, the old external enclosure in which I mounted a 500 GB HDD years ago came with such a power supply exactly so that it COULD be used with a desktop unit and not draw power from the computer's data port.
  5. @Paperdoc
    Thank you for continuing to address my issue. The enclosure is powered from the wall and is SATA III compatible. The USB 3.0 hub is also powered from the wall. For now, I connected the enclosure to the USB 3.0 port on the router. The access speeds are MUCH lower than what they should be for a USB 3.0 port (20 Mbs read, 6 Mbs write), but they are of course limited by the power of the router processor and the quality of the SAMBA server running on the router.
    I'm still wondering why the 4 TB and 500 GB external MBR HDDs run ok together on the same USB 3.0 HUB, but the 3 TB GPT external HDD runs only if by itself on the HUB, or attached to a separate USB 2.0 port.
  6. RE: your "still wondering ..." part. Re-read my second paragraph of Dec 18. Both the 4 TB and the 500 GB external HDD units are designed and marketed as "USB3" devices. This means they are designed to work with a power supply limited the 0.9 amp max. of a standard USB3 port, and they do. But your 3 TB system was not designed this way. It was an internal HDD that normally requires much more than 0.9 amps to operate, installed into an enclosure that can attach by USB3.This later unit cannot run with only the power that any standard USB3 port can supply. Its only hope is if the enclosure you mounted it in comes with its own power supply brick to provide the power needed by that internal HDD. If it gets enough power that way, then it can communicate with the USB3 port of a Hub or computer.
  7. @Paperdoc
    There may be 4TB external HDDs outthere which can be powered only through the USB bus on the laptop, but my Seagate is definitely NOT one of them. It needs to be powered from the brick (as you call it), or it won't work. Unlike the portable 500 GB which does not have a power port on it, being powered by the USB bus on the laptop, or in my case, by the powered (from the wall) USB 3.0 hub.
    So, the way I see it, they don't work together because they are both designed to be powered from the USB bus (one of them is NOT), but for some other reason I came here to find out.
    You seem to have missed my answer about how is the USB 3.0 enclosure powered. I repeat here, it is powered from its own brick, because it is designed to support drives larger than 4TB. The enclosure wprks, if connected by itself, either to the USB 3.0 port on the laptop, or to the USB 3.0 hub. It does not work (correctly) though, if paired on the hub with another USB 3.0 external HDD, but partitioned MBR. I don't have another USB. 3.0 external HDD partitioned GPT to check if it works when paired with the USB 3.0 enclosure. This is what I'm trying to find out on this forum. Why the enclosure with a GPT HDD does not work when paired with a USB 3.0 partitioned MBR? Can you help?
  8. I guess missed I missed a detail. If I got it right this time, that 3 TB internal HDD that you mounted in an enclosure actually has its own power "brick" (that came with the enclosure) so that is should not be drawing any power from the Hub. Correct? If yes, then power is not likely the problem.

    Re-reading all your posts, though, I realized that the other large (4 TB) Seagate external drive you are using with the USB3 Hub is seen by Windows as Partitioned in the MBR style. You are correct - that Partition system cannot handle any unit over 2 TB. So, IF it actually is functioning with its full 4 TB, then there must be some Seagate-supplied software doing some fancy manipulation. That then brings to mind two possible problems.

    1. Perhaps the special software is dealing with the 4 TB unit successfully, but cannot deal at the same time with a drive that uses GPT Partitioning. You might ask Seagate about that.
    2. To use any HDD partitioned using GPT under Windows, you must be using a 64-bit version of Windows with its included driver for such drives. The 32-bit versions do not have such drivers. Since you CAN use this 3 TB unit by itself, and you say the laptop's internal HDD also is set up in the GPT style, I expect that you must already be meeting this requirement. Thus, this is much less likely to be your trouble.
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