I'm trying to prevent automount on a device. The device contains only one FAT32 GPT partition.

I have set the GUID Partition attribute to 63 using gdisk (i.e. do not automount). I have also tried using Diskpart and GPT ATTRIBUTES to 0x8000000000000000 (i.e. no default drive letter).

While both these works on Windows 10, MacOS still mount my partition. How to prevent this on any computer I plug my device ?

I don't want to hide the partition because MacOS will ask to format. I don't want to add an entry to fstab because it works on a single computer only.

  • Asking macOS not to mount a partition is the same as hiding the partition. Your question contradicts itself. Clarify: Does the device contain only one partition? Or, is only one partition FAT32 formatted? Will you be manually mounting the partition when booted to Windows and/or macOS? – David Anderson Mar 7 at 20:15
  • The device contains only on the partition and I'll manually mount it. – Jean-Charbel VANNIER Mar 8 at 8:54
  • Does the drive have to be using a GPT? Can you use the legacy MBR partition table? – David Anderson Mar 8 at 10:47
  • If there is a solution with MBR but haven't found one yet. ATM I'm using GPT because windows respect the "no default drive letter" attribute. – Jean-Charbel VANNIER Mar 8 at 11:04
  • Is this device a flash drive or some other type of external drive? The attributes you refer to are only defined for Microsoft partition types. This would explain why they do not work with macOS. I can not get these attributes to work with a flash drive under macOS or Windows. Do you need the no auto-mount to work with macOS alone or with Windows? – David Anderson Mar 8 at 17:59

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