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User profile for user: jorhh
jorhh Author
User level: Level 1
43 points

M1 MacBook Air: Serious issues with external disks

I’m having serious trouble connecting external drives (Seagate 2.5" HD, Samsung SDD) to my M1 MBAir:

Everything is fine only when I connect the (USB 3.0) drives to the M1 MBAir via a USB C hub (powered or non-powered, doesn't make a difference).

However, whenever I connect the drives directly to the M1 MBAir, things fall apart:

Disk access is very slow or fails, disks eject fails, or disks are ejected at random. (It’s not the cables.)

I am worried that my brand new M1 MBA has a set of faulty ports.

Any help/input/ideas highly appreciated.

MacBook Air

Posted on Jan 7, 2021 6:07 AM

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User profile for user: jorhh
jorhh Author
User level: Level 1
43 points

Posted on Jan 10, 2021 9:37 AM

Hey there,

Thank you again for your kind help. It turned out that your "cable" hint was quite close to solving the mystery.

After a lot of testing ("start with what is working … and then go from there") I discovered that the effects observed were caused by a bunch of mixed software/hardware issues:

  • one of the three drives appeared to be kind-of-faulty (fine with the iMac, not with the MBAir) - I suspect power issues
  • I binned three USB-A-to-Micro-B "3.1" HD cables (the ones with the weirdly wide connector) since they caused issues
  • I also discovered that the two USB-C hubs I used caused all kind of intermittend connection problems with HDs
  • From time to time, the front Thunderbolt port of the MBAir stopped working completely - a restart got it working again

Two of the three drives used were totally fine when connected directly to the MBAir with a (new) USB-C-to-Micro-B HD cable.

Phew. What a mess.

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User profile for user: jorhh
jorhh Author
User level: Level 1
43 points

Jan 10, 2021 9:37 AM in response to Branta_uk

Hey there,

Thank you again for your kind help. It turned out that your "cable" hint was quite close to solving the mystery.

After a lot of testing ("start with what is working … and then go from there") I discovered that the effects observed were caused by a bunch of mixed software/hardware issues:

  • one of the three drives appeared to be kind-of-faulty (fine with the iMac, not with the MBAir) - I suspect power issues
  • I binned three USB-A-to-Micro-B "3.1" HD cables (the ones with the weirdly wide connector) since they caused issues
  • I also discovered that the two USB-C hubs I used caused all kind of intermittend connection problems with HDs
  • From time to time, the front Thunderbolt port of the MBAir stopped working completely - a restart got it working again

Two of the three drives used were totally fine when connected directly to the MBAir with a (new) USB-C-to-Micro-B HD cable.

Phew. What a mess.

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User profile for user: Branta_uk
Branta_uk
User level: Level 7
32,666 points

Jan 7, 2021 6:30 AM in response to jorhh

If the disk works OK when connected on an external hub you are using the same ports to make the connection which proves your MacBook and its USB ports are working correctly.


I would suspect either a software conflict (DON'T install the third party software provided with many external drives, your MacBook should be able to detect the device using native software),

--OR--

A power problem because the drive is demanding more than the Macbook's port can deliver, but this seems less likely as you say it also works on unpowered hubs. Check this point again, giving attention to whether the MacBook is on battery or external power when problems appear.


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User profile for user: jorhh
jorhh Author
User level: Level 1
43 points

Jan 7, 2021 12:43 PM in response to Branta_uk

Thanks for the input - I am also at a loss here (which is a bit of a first after 26 yrs of Macs).

I think I can rule out software interference - I tend to keep away from anything drive manufacturers provide ; )

Power might be an issue, however, the drives work even with the unpowered hub and/or MBAir. Unless there is some kind of communication error (i. e. drives not "requesting" enough power from the MBAir), I doubt this might apply.


The M1 MBAir also appears to have issues running/starting /finishing a proper Time Machine backup on those external drives (all with the USB C hub):

One disk got (for lack of a better word) “shredded” in the preparation stage (MBA noodles around a while “preparing the disk”, then complains about “unable to unmount” … and the disk no longer responds, just blinks … had to resurrect it with a Win10 PC … yikes)

On a different disk, Time Machine got stuck at a random point (“160GB”), didn’t seem to progress, and then reported a “full Time Machine disk” … on a 500GB disk for about 260GB of data. Not good.

And none of the disks have any issues on my iMac.

This is getting weirder by the minute.


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User profile for user: Branta_uk
Branta_uk
User level: Level 7
32,666 points

Jan 10, 2021 4:54 PM in response to jorhh

I'm glad to hear you are making progress, multiple faults always makes life interesting. I'll risk a wild guess that the problem might be the USB-A/microB cables unable to support the data rates on the new MacBook's ports when connected direct, but the older USB hub(s) had already forced a lower rate so the limitation in the final cable to the HDD was less visible. That's only a guess so no free beer if you find I'm wrong

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M1 MacBook Air: Serious issues with external disks

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