How to low-level format using a Mac?


Tags: Mac OS X

There are two ways to accomplish this:

Solution 1 - The easy solution (which might not work in some cases)

Select the disk (not the partition, but the actual disk -- select the one that is not named in a human readable form, it shows the size and a part number) in Disk Utility. Click the erase tab (not the partition tab!), and click security options. Choose Zero Out Data. Then click erase on the erase tab.

Solution 2 - For experts only

If you are a little more experienced you can also use the shell. But only do this if you know what you are doing!

Use Disk Utility to find the actual device name used by the disk you want to erase (f.e. /dev/disk3). It is really important that you get this right I can not stress this enough! Once you know the actual device name fire up a shell and run this command (where you replace "X" with the correct number):

sudo dd if=/dev/zero of=/dev/diskX

If you receive an error like "Resource busy" than at least one partition of your disk is probably mounted and you have to umount it first. Use the command:

sudo mount

to find out what volumes are mounted. And now run this command for every partition of your designated drive which is mounted (where you replace "X" with the correct drive number and "Y" with the correct partition number:

sudo unmount /dev/diskXsY

Once you have unmounted all partitions you should be able to run the dd-command above sucessfully.

And once more: The dd command above destroys ALL DATA without even asking! So make absolutely sure you get this right OR leave it alone if you have any doubt!

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