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NTFS drives & mobile devices

Why your drive may appear as read-only on iPhone or Android — and how to fix it.

iPhones and Android phones cannot write to NTFS drives. iOS and Android can read NTFS, but neither platform includes a built-in NTFS write driver. If your drive is formatted as NTFS, ColdCopy can browse your files but cannot save new backups. You need to reformat to exFAT or FAT32.

What is NTFS?

NTFS (New Technology File System) is the default file system used by Windows. While macOS, iOS, and Android can read NTFS drives, none of these platforms include a built-in NTFS write driver — Apple and Google have not licensed the write implementation from Microsoft.

This means ColdCopy — like every other mobile app — physically cannot write files to an NTFS-formatted drive.

How to check your drive's format

On a Mac

  1. Connect the drive to your Mac.
  2. Open Disk Utility (Applications → Utilities → Disk Utility).
  3. Select your drive in the left sidebar.
  4. The format is shown in the top-right area. If it says Windows NT Filesystem, it's NTFS.

On Windows

  1. Open File Explorer and right-click your drive.
  2. Select Properties.
  3. The File system field shows the format.

Choosing the right format

Format Mac Windows iOS & Android / ColdCopy Max file size
exFAT Read & Write Read & Write Read & Write No practical limit
FAT32 Read & Write Read & Write Read & Write 4 GB per file
APFS Read & Write Not supported Read & Write No practical limit
NTFS Read only Read & Write Read only No practical limit

Recommendation: use exFAT. It works natively on iPhone, Mac, and Windows with no file-size limit. It's the best choice for a backup drive you'll use across multiple platforms.

How to reformat your drive

Warning: reformatting erases all data on the drive. Copy any important files to another location first.

On a Mac (recommended)

1

Open Disk Utility

Applications → Utilities → Disk Utility

2

Select your drive

Click the drive in the left sidebar (the top-level disk, not a partition).

3

Click Erase

Click the Erase button in the toolbar.

4

Choose exFAT

Set Format to ExFAT, give the drive a name, then click Erase.

On Windows

  1. Open File Explorer and right-click the drive.
  2. Select Format…
  3. Set File system to exFAT.
  4. Click Start to reformat.

After reformatting

Once the drive is formatted as exFAT (or FAT32), connect it to your phone using a USB-C cable, Lightning to USB 3 adapter (older iPhones), or USB OTG adapter (Android). ColdCopy will detect the drive and display it as ready for backup.

If the drive still shows as read-only after reformatting, try:

SMB / Network drives

ColdCopy also supports backing up to SMB network shares (e.g. a NAS or a shared Mac folder). Permissions on the network share itself must allow write access for the user account you connect with. If you can browse the share but files won't copy, check the share permissions on the host machine.

Drive still not working? Contact us and we'll help troubleshoot.

contact@lidavi.com