How to low level format an external hard drive on Yosemite

I need to perform a low level format on an external hard drive as the WD external hard drive does't provide instructions for doing it on my Mac with Yosemite.

iMac (27-inch Mid 2010), OS X Mavericks (10.9.3)

Posted on Nov 15, 2014 12:35 PM

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2 replies

Nov 15, 2014 12:49 PM in response to golfnutbw

Drive Partition and Format


1. Open Disk Utility in your Utilities folder.


2. After DU loads select your hard drive (this is the entry with the mfgr.'s ID and size) from the left side list. Click on the Partition tab in the DU main window.


3. Under the Volume Scheme heading set the number of partitions from the drop down menu to one. Click on the Options button, set the partition scheme to GUID then click on the OK button. Set the format type to Mac OS Extended (Journaled.) Click on the Apply button and wait until the process has completed.


4. Select the volume you just created (this is the sub-entry under the drive entry) from the left side list. Click on the Erase tab in the DU main window.


5. Set the format type to Mac OS Extended (Journaled.) Click on the Security button, check the button for Zero Data and click on OK to return to the Erase window.


6. Click on the Erase button. The format process can take up to several hours depending upon the drive size.

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How to low level format an external hard drive on Yosemite

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