Reader's question: Is there a sequence for connecting or disconnecting devices to the USB hub?

Reader question: connecting devices to the USB hub

I recently received an interesting question from my reader Wolfgang:

4 external hard drives, 2 printers, 1 scanner and a LaCie BlueRay recorder are connected to the Mac via an old USB hub. Now I've bought a new USB 3.0 hub and don't want to make any mistakes when connecting!

Hence my questions that you will probably laugh at:

  1. Can I make all new connections with all devices switched off?
  2. In which order do I have to proceed?
  3. Can I leave the Mac turned on and simply remove all connection cables without causing damage?
In which order should devices be plugged in or unplugged from the USB hub? Here is Sir Apfelot's answer (Photos: Sir Apfelot).

In which order should devices be plugged in or unplugged from the USB hub? Here is Sir Apfelot's answer (Photos: Sir Apfelot).

Answer from Sir Apfelot

I wrote the following answer to Wolfgang:

With USB hubs you can really only make one mistake: Disconnect hard drives (or USB sticks or other media to which is written) from the Mac - either by unplugging the hub or by unplugging the hard drive itself. For printers and scanners and Even with the Blu-ray recorder (if it is not burning), nothing can happen if you simply disconnect them, but hard disks can under certain circumstances run into problems if you unplug them exactly when they open the table of contents of the disk after a write process To update. If you catch the wrong moment here, the entire hard drive can become illegible and you have to go with one Data recovery program try to restore the content structure.

That means in short:

  • The devices can be plugged in in any state. Regardless of whether the Mac or the hub is on or off. It does not matter.
  • You should only unplug hard drives (or USB sticks, SD cards) after you have ejected them in the Finder.

You can eject the volumes in the Finder either via the small "Eject" symbol next to the volume name or by right-clicking on the volume and then selecting "Eject XYZ".

Before unplugging writable media from the Mac or a hub, you should eject it using the button in the Finder.

Before unplugging writable media from the Mac or a hub, you should eject it using the button in the Finder.

Alternatively, you can right-click on the symbol of the hard drive or the medium and select the item "Eject volume name".

Alternatively, you can right-click on the symbol of the hard drive or the medium and select the item "Eject volume name".

You can also plug the hub into the Mac at any time. It doesn't matter whether the Mac is on or off or whether the hub is on or off. After plugging in the hub, the Mac also registers all connected hard drives and other media.

Damage to the Mac or hard drive from unplugging

Another important point: As far as I know, neither the hard drive nor the Mac can take "real" damage if you unplug devices from the hub. Even if you remove the hard drives or other media without first logging them out, the maximum possible result is "data damage", but in my opinion not to hardware damage.

Please don't nail me to it though. Whenever possible, you should always de-register the volume in the Finder before physically removing it from the Mac or the hub. Then nothing can actually go wrong ...

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4 comments

  1. D says:

    If the USB hub does not have its own power supply, but the connected devices draw too much power, the Mac may deactivate the USB port for overvoltage protection reasons. This is of course stupid when hard drives have already started operating. As a first test, it may not be entirely wrong to turn off the Mac, connect all devices while they are switched on and only then turn on the Mac. If that works, the order shouldn't really matter. If not: Disconnect all consumers without their own power supply and after the next restart, plug them in again one after the other with a short delay to find out which device is drawing too much current. In this case, a USB hub with its own power supply is recommended.

    • Sir Apfelot says:

      Yes, that's a good indication. I sometimes have passive (unpowered) hubs that are on the verge of failure. Then the two connected 2,5 inch hard drives run through and suddenly one of them logs off. Of course, this must not happen if a write process is in progress. For this reason - as soon as you have connected more than one external hard drive without its own power supply - I would use an active USB hub. I have one here via the Amazon search Link created in which some USB 3 hubs with power supply from well-known manufacturers fall out. Unfortunately, there are many non-name providers who change their company name every few months in order to avoid the warranty. You can already imagine how "good" their products are.

  2. Philip says:

    There are numerous devices attached to my USB hub: is there a way to eject the entire USB hub or at least eject all devices at once so that you don't have to do everything individually?

    • Sir Apfelot says:

      Hello Philip! Have a look at my article about "CleanMyDrive 2". I think that could eject all connected hard drives with one click. I just don't know whether it will still work under Catalina. :(

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