4

I have a 1TB external hard drive. It's formatted as exFAT using 1024kb allocation unit size. I will be using this hard drive on Mac and Windows both for making backup from time to time.

I have a problem that files saved on Windows are not visible for Mac system and vice versa - Windows doesn't see files saved on Mac. For example:

  1. I connected hard drive to Windows and copied def.svg file there.
  2. I disconnected the hard drive and connected to Mac - def.svg is not visible.
  3. I copied abc.mp3 file on Mac and disconnected the drive.
  4. I connected to Windows again - abc.mp3 is not visible, only def.svg.
Improve this question
7
  • I think it's your allocation block size, should be 128KB See partitionwizard.com/partitionmagic/… The trick, if you don't have anything important on there yet, is to reformat it on the Mac, Disk Utility, as MBR/ExFAT. That will do it correctly & won't even allow you to set a custom value.
    – Tetsujin
    Commented Oct 13, 2022 at 14:34
  • @Tetsujin - done; I reformatted the disk on Mac, using Disk Utility as exFAT. But the problem is not resolved. What's more, a file previously saved on Widows (def.svg) is not deleted (after reformat) :/
    – Mateusz Żur
    Commented Oct 13, 2022 at 17:47
  • …then clearly there was something wrong with the reformat. Make sure you select the device, not the volume. Cmd/2 will show all devices. Select 'Erase' & then choose ExFAT & Master Boot Record.
    – Tetsujin
    Commented Oct 13, 2022 at 17:50
  • Yes, you are correct! I was reformatting volume, not a whole disk. Now it works. Thank you :)
    – Mateusz Żur
    Commented Oct 13, 2022 at 18:03
  • Good news!! :) Let me put that in as a quick answer [I wasn't certain I was right, hence just a comment to start with]
    – Tetsujin
    Commented Oct 13, 2022 at 18:11

1 Answer 1

Reset to default
3

Strictly, the allocation block size for a a 1TB drive should be 128KB - Ref: What Is the Best Allocation Unit Size for exFAT & How to Reset It [Partition Magic]

macOS just doesn't like non-standard formats. It makes assumptions that will 'break' when data is exchanged between OSes.

The simplest way to fix this, if there is no vital data to be backed up first, is to just reformat on the Mac, which will adhere to strict standards other formatters may allow to be flexible.

From Disk Utility, select the entire device ( Cmd ⌘ 2 will show devices rather than just volumes) then click Erase & choose ExFAT & Master Boot Record.

Improve this answer

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .