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19 February 2024  Jennifer Thatcher  Technology Manager of Test Dept.
 

Summary
Learn how to fix the issue of not being able to modify or write files on your mobile hard disk connected to a Mac. Also, discover a data recovery method.



Table of contents

table iconI. The reason why the mobile hard disk can only be read but not written on Mac
table iconII. Use Renee Undeleter to Recover Important Data from Hard Drive on Mac
table iconIII. The solution that the mobile hard disk can only be read but not written on Mac
external hard drive read only mac

I. The reason why the mobile hard disk can only be read but not written on Mac

After connecting the mobile hard disk to the Mac computer, the reasons why it can only read but not write may be as follows:

1. The file system of the mobile hard disk is NTFS

NTFS (New Technology File System) is a log file system developed by Microsoft Corporation. It keeps a log of all changes, making it easier to restore in case of errors. Mac OS X can only read NTFS, not write to it. To solve this, reformat the disk or use third-party software for reading and writing NTFS drives on Mac. Accessible reformat it or use the available on Mac Third-party software for reading and writing NTFS hard drives to solve.

2. Set the read-only permission on the mobile hard disk

When the mobile hard disk on a Mac is set to read-only, it can only be read and not modified or written. In this case, the permissions can be checked and modified.

3. A format error occurred in the mobile hard disk

If there is a formatting error in the mobile hard disk, when connecting it to a Mac computer, a prompt may pop up, indicating that the device can only be mounted in read-only mode during connection, and the mobile device can only read but not write. able to pass repair hard drive to solve.
After understanding the reasons why the mobile hard disk can only be read but not written on the Mac, the following will introduce several solutions for you. Since some solutions will clear the files in the mobile hard disk, in order to prevent the loss of important data, you can connect the mobile hard disk to other computers that can read and write, and back up the files. Or use data recovery software to scan and restore/extract files on the hard disk. If there is no important data, you can check the solution that the mobile hard disk can only read but not write.

II. Use Renee Undeleter to Recover Important Data from Hard Drive on Mac

1. What is Renee Undeleter?

Renee Undeleter is specialized software for restoring various data files. It can recover lost data from accidental deletion, empty recycle bin, or disk formatting. The software includes four functional modules: file recovery, format recovery, partition recovery, and image creation, providing a comprehensive solution for all data loss issues.
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Easy to use Recover data by 3 steps;

Multiple scan modes Fast partition scan, whole partition scan and whole disk scan;

Supported file types Image, video, audio, text, email and so on;

Image creation Create a partition image to read and back up data;

Supported devices SD card, SDHC, SDXC, USB flash drive, hard disk and computer.

Easy to use Recover data by 3 steps;

Multiple scan modes Fast partition/whole partition/whole disk scan;

Supported devices SD card/USB/hard disk.

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2. How to use Renee Undeleter to recover mobile hard disk data?

Step 1: Download, install and run Renee Undeleter on a Mac computer, and select the (Whole Partition Scan) option on the main interface.
Note: Do not install on the disk that needs to restore data, so as not to cause data overwriting.
select whole partition scan in renee undeleter on mac
Data recovery function introduction:

Fast Partition Scan – Quickly retrieve files lost due to accidental deletion or emptying the recycle bin.

Whole Partition Scan – Quickly recover files lost due to inaccessible or formatted partitions.

Whole Disk Scan – Analyze and get partition information and perform a full scan of the entire partition.

Image Creation – You can create a mirror image for a partition to back up the current partition state.

Step 2: Next select the hard disk partition from which you want to recover/extract data. After the selection is complete, click (Next).
Select the partition to scan for the Mac version
Step 3: Wait for the scan to complete, preview the file by double-clicking, and if the desired file is found, check it and click the (Recover) button.
Note: It is recommended to save the recovered files in other partitions instead of the original hard disk to avoid data overwriting. If this recovery mode does not find the required files, you can also try to use the (partition recovery) mode for a more comprehensive scan.
preview before recovery

III. The solution that the mobile hard disk can only be read but not written on Mac

1. Format the mobile hard disk to change its file system

When the file system of the mobile hard disk is NTFS, it can only be read and not written on a Mac. To enable both reading and writing, the file system can be formatted to one supported by the Mac system. However, this process will erase all data on the mobile hard disk, so please back up the data beforehand.
Step 1: Find and click on Disk Utility in the launchpad; alternatively, click on Finder > Applications > Utilities to locate and open Disk Utility.
Encrypt USB Drive in Mac OS open disk utility in macos
Step 2: Select the target mobile hard disk on the left, click (Erase) at the top, choose the file system format, and then click (Erase).
Tip: If the mobile hard disk is used to store Time Machine backups or only for Mac systems, you can select (Mac OS Extended (Journaled)); if the mobile hard disk needs to be used for both Mac and Windows systems to store data, then you can Select (ExFAT). If you want to use the mobile hard disk in some older models that do not support exFAT, you need to select (MS-DOS (FAT)), but the FAT file system cannot be used on hard disks larger than 32GB.
erase hard disk drive when it is not showing up in mac

2. Use third-party software to read NTFS hard disk

If there is a large amount of important file data on the mobile hard disk that cannot be formatted, third-party software like Paragon NTFS For Mac, Tuxera NTFS For Mac, or Mounty For NTFS can be used to read the NTFS hard disk on Mac. These software options allow users to perform unlimited read and write operations on NTFS hard disk partitions in the Mac system, but they usually come with a charge.

3. Change the read and write permissions of the mobile hard disk

When the permission of the mobile hard disk in the Mac system is read-only, the user cannot perform any write operations. Changing the permission of the mobile hard disk can solve this issue.
Mobile hard disk read-only
Steps: Right-click the mobile hard disk, select (Show Profile), and change the permission from (read-only) to (read and write) in the (Sharing and Permissions) column.
Modify permissions to read and write

4. Repair mobile hard disk errors

To fix a formatting error on a mobile hard disk that is only readable but not writable on a Mac, follow these steps. Note that this process may result in data loss, so it is recommended to backup your data beforehand.
Step 1: Find and click on Disk Utility in the launchpad; alternatively, click on Finder > Applications > Utilities to locate and open Disk Utility.
Encrypt USB Drive in Mac OS open disk utility in macos
Step 2: Select your hard disk in the list on the left, and then select the (First Aid) function above.
Step 3: Clicking (First Aid) will prompt a confirmation window to appear, indicating that the function will check for errors and repair the volume. Click (Run) to begin the hard disk checking and repairing process.
run first aid in mac disk utility