Home > Questions

Time Machine backup drive not mounting on macOS Ventura?

Hi, I have split my Lacie Rugged 4TB external hard drive into two partitions. One for photos and another for daily backup of my Mac. The Photos partition is mounting fine but the Time Machine backup partition is not. They can both mount on my new MacBook Air that doesn't have Ventura. Is this a Ventura bug?

Best Answered by

iBoysoft author Jenny Zeng

Jenny Zeng

Answered on Tuesday, August 5, 2025

Your Time Machine backup disk or partition should have no problem mounting on macOS Ventura or other versions. If it suddenly becomes grayed out in Disk Utility, you can try the following steps to fix it.

First, safely eject the external hard drive from your Mac and pull it out. Then reboot your Mac and reconnect the drive. Hopefully, the Time Machine backup partition is mounted now. If not, open Disk Utility, select the backup partition, and click the Mount button at the toolbar to manually mount it. 

What else you can try is to force mount the partition in Terminal. Here's how to do it:

  1. Open Terminal from your Applications/Utilities folder.
  2. Enter the following command and press the Enter key.diskutil list
  3. Note down the disk identifier of the backup partition, such as disk2s2.
  4. Execute the following command to force mount the partition. (Replace disk_identiifer)diskutil mount /dev/disk_identifier

Suppose it still doesn't do the trick, then you can select the partition and click First Aid to check and repair disk errors.

If Disk Utility can't repair it, the last straw is to reformat the backup partition, which will erase all data on it. That being said, you need to recover the important files beforehand. To retrieve files from the unmountable backup drive on Mac, you'll need a professional data recovery tool like iBoysoft Data Recovery for Mac.

Click the button below to scan your unmountable drive and preview files for free.

Read also:

External Hard Drive Not Mounting on Mac Computer, How to Fix?

People Also Ask

Read More Questions

Read More Advice From iBoysoft's Computer Experts

The copy of the installer app failed

'The Copy of the Installer App Failed', Why & How to Fix

Follow the methods for fixing 'The copy of the installer app failed' in Terminal. Learn why you fail to create a macOS bootable installer with Terminal.

Disk0s2 not mounted on Mac

Disk0s2 Greyed Out: Could Not Mount Disk0s2 (Solutions)

This article tells you what disk0s2 on Mac is, how to fix disk0s2 not mounted and what to do if receiving the message 'the container /dev/disk0s2 could not be verified completely.'