4TB drive becomes 1.8T


I have a used Dell Sata drive. It's a 4TB. It reads on Disk Utility as 1.8T. I formatted and ran first aid. It still reads as 1.8TB in size. Is there a way to make this drive a 4TB again?


Rosie Moderator
Staff member
If it is a 4 TB disk, and Disk Utility only finds 1.8 TB, I bet it was partitioned. Use Disk Utility and check the external list of drives.

In the View Menu at the top left of the Disk Utility window select Show All Devices.
Now in the external list you should see the Dell Drive with a possible name of the model.
Click on that and have it reformatted.


What format is the drive now? You can get info on the drive, or launch Disk Utility, and that will show you.
Make sure that the View setting is for "Show All Devices", then select the device -- not a partition. The device will show the manufacturer's info, such as the model number. With the device selected, choose Erase. Change the format scheme to GUID, and the format to Mac OS Extended (journaled). And, finally, click Erase. You should now see all of the space.
If you still don't see the 4TB (or very close to that), and it is an external drive, then I suspect that your external enclosure is simply not compatible with larger hard drives.