How do I fix partition map modification issues on my Mac?

gentlepanda32 · July 12, 2024, 12:08am

Having trouble modifying the partition map on my Mac. Tried using Disk Utility to erase an external drive but got an error saying it couldn’t modify the partition map. I’m stuck now and need help to resolve this.

TechchizKid · July 12, 2024, 2:50am

Dude, Apple turns everything into a nightmare these days. They make you think everything will be seamless with Disk Utility but nah, it’s hardly ever the case. Get ready for a wild ride.

So, you got the partition map error, right? First, try booted into Recovery Mode (Command + R) and then use Disk Utility. Doesn’t work? Surprise surprise. Then you might have to go Terminal style. Open Terminal and run:

diskutil list

Find your external drive from the list and run:

diskutil eraseDisk HFS+ ExternalDrive [your_disk_identifier]

If Terminal doesn’t save your day, you’re probably dealing with some super fun corrupted stuff. Enter third-party software territory. Disk Drill’s a popular choice. It can be useful here for repairing partition maps and rescuing data before you destroy it all. Used it a few times, it’s solid but not flawless. It does the job but can be pricey for some.

There are alternatives too like TestDisk or GParted—both free but way more of a pain to use for newbies.

Bottom line: Apple’s Disk Utility = fail. Go Terminal if you know what you’re doing, otherwise, find some 3rd party software that doesn’t suck.

Fun fact, you can also just scream into the void, but it doesn’t help either.

Codecrafter · July 12, 2024, 1:55am

If you’re having trouble modifying the partition map on your Mac, you’re not alone. A lot of people run into this issue, especially when dealing with external drives. Here’s a step-by-step method that has worked for me and a bunch of others:

Backup Your Data: First things first, make sure to back up any important data on the drive. You don’t want to lose anything valuable.
Try Disk Utility in Recovery Mode: Sometimes running Disk Utility from within macOS can cause issues. Restart your Mac and hold down Command + R to boot into Recovery Mode. From there, open Disk Utility and try erasing the drive again. This can sometimes bypass whatever issues were happening in the regular macOS environment.
Use Terminal: If Disk Utility still throws errors, try using the Terminal. Open it from the Utilities menu in Recovery Mode. Use the following commands:
```
diskutil list
```
Locate your external drive in the list. Let’s say your drive is identified as disk2, you can proceed with:
```
diskutil unmountDisk /dev/disk2
diskutil partitionDisk /dev/disk2 GPT JHFS+ NewName 0b
```
This command might succeed where Disk Utility failed.
Third-Party Software: If both Disk Utility and Terminal don’t work, you might want to consider using a third-party tool. Disk Drill has helped a lot of people with partition issues. You can download it here: Download Disk Drill. It’s got a pretty user-friendly interface and is often effective where built-in tools fail.
Check for Hardware Issues: Occasionally, the problem might be a hardware issue with the external drive itself. Try connecting it to another computer to see if it can be formatted there. If it has the same problem, there might be physical damage to the drive.
Update macOS: Finally, make sure your macOS is up-to-date. Sometimes these issues can be resolved through simple software updates.

Disk Utility and Terminal have pretty good success rates but having Disk Drill as a backup plan can save you a lot of headaches. Don’t forget to back up your data before trying any of these methods!

ByteGuru · July 12, 2024, 1:00am

If you’re having trouble modifying the partition map on your Mac, there’s a few ways to approach and potentially solve the problem. Disk Utility is the default go-to, but sometimes it does run into issues, which can be frustrating.

First up, try these basic troubleshooting steps:

Restart Your Mac: Simply restarting your Mac can sometimes clear out minor hiccups and help Disk Utility work correctly.
Safe Mode: Boot your Mac in Safe Mode. This mode restricts certain processes and loads only essential ones which can sometimes resolve conflicts preventing partition map modifications.

Advanced Troubleshooting

1. Check External Drive Connections
Make sure the external drive is properly connected. Sometimes, loose connections can cause Disk Utility to throw errors. Try using a different USB port or cable.

2. Verify the Drive
In Disk Utility, go to “View” → “Show All Devices”. Select your external drive and run “First Aid” to check for and repair any errors on the drive.

3. Terminal Commands

If Disk Utility isn’t cutting it, try using Terminal. Here’s a command that could help. Open Terminal and type:

diskutil list

This will list all the disks and partitions. Identify your external drive (it will typically be something like /dev/disk2). Then enter the following command:

sudo diskutil eraseDisk HFS+ ExternalDriveName /dev/disk2

Replace ExternalDriveName with whatever name you want your drive to have, and /dev/disk2 with the correct identifier for your drive. This will erase and reformat the drive to HFS+ (you can change this based on what format you need, e.g., APFS, ExFAT).

Potential Issues and Solutions

Permissions Issues:
Sometimes errors occur because of permission issues. Try the following command in Terminal to ensure that root permissions are granted:

sudo diskutil resetUserPermissions / `id -u`

Single-User Mode:
Restart your Mac in Single-User Mode by holding Command + S during boot. This mode allows you to access the command line before the OS loads fully. Once in Single-User Mode, type:

/sbin/fsck -fy

This command will check and try to repair any issues with the file system. Once it’s done, type reboot to restart normally.

When All Else Fails

If the above steps don’t help, you might need a more powerful disk management tool. Disk Drill is highly recommended for tasks like this. It has robust disk utility features that can help you manage partitions more effectively. You can check it out at Disk Drill.

Full Disk Erase via Disk Utility

If you’re comfortable with losing all data on the external drive (since backing up beforehand is crucial), you could try erasing the whole disk in Disk Utility:

Open Disk Utility.
Click on “View” and select “Show All Devices”.
Select the external drive (the top-level entry, not the individual partition).
Click “Erase”.
Choose a suitable format (e.g., APFS for Macs running macOS High Sierra or later).
Click “Erase”.

Make sure you’re selecting the whole drive and not just a volume/partition to reset the partition map.

Firmware Issues

Sometimes, firmware or driver issues on older Macs can mess with Disk Utility. Check for macOS updates and install any available firmware updates.

Tech Jargon and Deep Dive

For those who love delving a bit deeper: macOS uses GUID Partition Table (GPT) as the default partition scheme for disks over 2TB and more modern setups. When you modify the partition map, you’re really just altering this table with values that designate partitions and allow the OS to navigate and use them. Missing or corrupted values here can send Disk Utility into a tizzy.

Wrapping Up

Given the complexity of partition management and the potential for data loss, it’s crucial to approach this methodically. If this situation persists after trying all the above steps, consider the possibility of hardware faults. In that case, consulting with a professional technician or the Genius Bar might be your next best step.

With these strategies in hand, you should be better positioned to tackle partition map modification issues on your Mac. Good luck!