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4TB External Hard Drive Mounted But Won't Write on Mac

I have a 4 TB Seagate external hard drive (3.42 TB available) mounted on my Mac running El Captain 10.11.4. I wanted to add a folder of photos to the drive, but it won't let me. I discovered that the external hard drive was not writable. I Ran First Aid, and now it says it is writable, but when I try to drag and drop my folder to the hard drive, it won't stay. I also checked Get Info, it says “You can only read” under “sharing & permissions.” Does anyone know how to fix that?

Best Answered by

Connie Yang

Answered on Tuesday, August 27, 2024

Check whether your external hard drive is formatted with NTFS.

NTFS is a file system originally for Windows. Apple only has the read privilege to Microsoft NTFS. To write to NTFS on a Mac, you can use iBoysoft NTFS for Mac to mount in read and write mode.

 Download

iBoysoft NTFS for Mac

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If your drive is not NTFS, it probably has some errors that even First Aid can't fix. Your only choice is to reformat it. However, reformatting the drive will erase all contents on it. You can copy files from the drive to your Mac before formatting.

  1. Open Disk Utility.
  2. Select the external drive on the sidebar.
  3. Click Erase on the toolbar.
  4. Rename the drive, choose a file system, and click Erase.

If you use the drive on both Windows and macOS, choose exFAT or FAT.