Disk Utility hangs on partitioning external 4T drive

The Disk Utility hanging during the partitioning process can certainly be frustrating. From your description, it appears the process has been running for an unusually long time. While it's possible for partitioning large drives like yours to take a few hours, it usually doesn't last for 12 hours.

Before we go forward, I'd suggest to safely cancel the current partitioning process, if it's still running. Be careful not to unplug or forcefully interrupt the process as it might cause data corruption. Instead, you can cancel it by clicking the stop button if it appears, or safely force-quit the Disk Utility from the Apple menu > Force Quit, and choose Disk Utility.

Once that's done, try to reboot your iMac. A fresh start can often solve many problems. Afterwards, open Disk Utility and run 'First Aid' on the drive to ensure its integrity before we try partitioning it again.

If the drive checks out okay with First Aid, let's try partitioning it once more. When you do, make sure your iMac is connected to a power source and not set to go to sleep in the middle of the process. This is a resource-intensive task, and any interruptions can cause the process to hang or fail.

Here are some helpful links with more information:

1. How to safely force-quit an application - Apple Support

2. Disk Utility for Mac: Disk Utility First Aid - Apple Support

3. About Disk Utility on Mac - Apple Support

Remember to always keep a backup of important data before you start partitioning or performing other significant tasks with Disk Utility.

Hi jeepme,

We see you have a question about partitioning an external hard drive. The amount of time required for that process would vary depending on a number of factors, including the size and speed of the drive, the cable type, and your Mac. Has it made any progress since you posted here?

Generally, it would be best to let it continue working as long as the progress hasn't stalled entirely. However, interrupting the process could risk any data on the external drive. Was it a new drive, or did it have content on it? If it's a new drive and it hasn't made any progress since you posted, that's when you may want to try erasing it and starting the partition process again:

Erase and reformat a storage device in Disk Utility on Mac - Apple Support

Partition a physical disk in Disk Utility on Mac - Apple Support

Cheers.

If the external drive is a hard drive, then modifying partitions & moving data can take days. The process should be faster with an SSD, but it depends on the SSD since some SSDs can become very slow when writing large amounts of data. Older hard drives may be wearing out or possibly may even be starting to fail which can increase the time it takes.

FYI, it is never a good idea to modify partitions as it is always risky and there is always a possibility of data loss. There are very few good reasons to have multiple partitions on an external drive. I hope you are not trying to use a single external drive for backups and data storage because how are you going to backup the data partition. I certainly hope you have a backup of the data on the existing partitions before you tried modifying the partition layout.