External SSD malfunctions on a Macbook Pro M1 but works on Windows

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External SSD malfunctions on a Macbook Pro M1 but works on Windows

Hi everyone,

I recently bought a MacBook Pro M1 and a Sandisk SSD. The external ssd works well on a Windows computer. However, when I use it on my Mac (with the applicable format), it works at first but fails later. It can not write or read data and sometimes ejects it by itself.

I can not repair it from Disk Utility. I get the error message 'Fixing damaged partition map. POSIX reports: The operation couldn’t be completed. Input/output error. : (5)' Also, I can not erase it from the Disk Utility. This time it says 'The volume on disk4 couldn’t be unmounted because it is in use by process 0 (kernel).Couldn’t unmount disk. : (-69888)'

I tried doing from the terminal. It worked but after I write two documents (pdf or zip file containing pdfs) on my ssd, it fails again. I can fix from Windows and use it. But after some documents, I get the same result. The ssd seems good on Windows. I can use it normally there. But on a Mac it malfunctions. I could not find the reason. How can I fix it?

Thank you.

P.S.: I tried all formatting types(APFS, Mac OS extended, ExFAT) and still got the same result.

Posted on Jul 18, 2021 4:27 PM

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Answer 1

Top-ranking reply

HWTech

Level 9

60,614 points

Jul 18, 2021 5:28 PM in response to kaanatak

Not all external USB drives are compatible with an M1 Mac. Unfortunately I have not seen any detailed reports about the issue except that a couple of users on these forums did confirm that the JMicron USB controller used by some external drives and devices was not compatible and this was confirmed by a reputable vendor online who was selling a product with a JMicron chipset. It is unknown for sure whether any other brands of USB controllers/chipsets are affected. All I know is that my external devices use an ASMedia USB controller chipset and I have never experienced an issue although I have not really used these devices much with my M1 Mac.

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Answer 2

kaanatak Author

Level 1

6 points

Jul 19, 2021 6:06 PM in response to HWTech

Throughout the day I tried many things. Thank you very much for the advice. I also tried some of them. But finally I solved it by first restarting the Mac, then formatting my external ssd on a Windows PC to exFAT with aus 128 kb. Then I inserted my ssd to my Mac and used first aid before erasing the ssd. Then I erased it into exFAT format (GUID). Now, it works fine. I tried many things so, I do not know where exactly the problem was but this process fixed it.

P.S.: Thank you very much for the possible solutions. It did not directly solve my problem but I learned a lot.

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Answer 3

HWTech

Level 9

60,614 points

Jul 19, 2021 5:11 PM in response to kaanatak

Make sure to connect the drive directly to the laptop. If you need to use an adapter, then try using another adapter especially a different brand. Also try using the other USB-C port on the laptop and try rotating the USB-C connector 180 degrees upside down. I know this is crazy, but it can sometimes work (usually indicating a half bad USB-C port).

If the drive has a removable USB cable, then try using another USB cable with the drive.

It is possible the drive has a problem or is not getting enough power.

Try restarting the laptop.

Try booting into Safe Mode which should disable most third party software.

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Answer 4

kaanatak Author

Level 1

6 points

Jul 19, 2021 8:13 AM in response to HWTech

Thank you very much for your answer. Now, I checked my ssd again. I could not find the info for the usb controller of my device. But on the internet I see from the descriptions that it is compatible with Mac and also there were videos of people using it on a Mac. So, I think this is not the cause for it. And actually Mac sees my ssd but after some point it kinda crashes. It can not read and write and data inside becomes invisible and later it ejects it. I could not understand.

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External SSD malfunctions on a Macbook Pro M1 but works on Windows

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