Is it possible to do a 'force formatting'?

Question

Is it possible to do a 'force formatting'?

I decided to erase the external USB HD I was using for Time Machine. I used TM with a password.

Well, when I opened Disk Utility, it asked me for a password twice.

After I gave the password and clicked ERASE, I wasn't able to acess my external USB HD anymore.

Disk Utility recognizes the external HD, however, it will not mount an icon on my Finder.

I am able to Verify and even Repair my external USB HD, but I don't see the erase tab anymore.

The USB HD is working perfectly well, I hear the spinning sound and the little blue light lights up.

I tried diferent ports and switching cables. No go.

Thanks in advance for your help 😉

MacBook Pro 17, Mac OS X (10.7.1)

Posted on Sep 16, 2012 7:54 PM

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Answer 1

den.thed

Level 9

77,050 points

Sep 16, 2012 9:09 PM in response to Camarillo Brillo

Hey Frank Z....

1. Connect the External HD and open Disk Utility in your Utilities Folder.

2. Highlight the HDs top icon in the list of drives and select the Partition tab.

3. Under Volume Scheme select 1 Partition and click on the Options... button.

4. Select GUID Partition Table in the drop down window and click OK.

5. Set the Format to Mac OS Extended (Journaled), name it and click the Apply button.

6. Once thats done, go to the Time Machine preference and setup TM to use or not use the drive.

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Answer 2

Sep 16, 2012 9:20 PM in response to den.thed

Hi den!

You see, that's the issue: although I do see my HD listed in Disk Utility, I have no access to it.

I see the partion tab, but once there, all the options are grayed out 😟

Bizarre...

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Answer 3

den.thed

Level 9

77,050 points

Sep 16, 2012 9:33 PM in response to Camarillo Brillo

What about the Mount and Eject buttons?

If the Mount button is blue click on it.

If it's not blue, click on the Eject button, disconnect the drive, quit Disk Utility, reconnect the drive, open Disk Utility and try the instructions above.

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Answer 4

Sep 16, 2012 9:43 PM in response to den.thed

Everything's grayed out, den.

Perhaps I have created a Windows format HD?

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Answer 5

den.thed

Level 9

77,050 points

Sep 16, 2012 10:19 PM in response to Camarillo Brillo

I see the problem, the problem is I've never had the problem.

However, I found > External HDD Unlock: Apple Support Communities which looks like a solution to the problem.

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Answer 6

Sep 16, 2012 10:27 PM in response to den.thed

Wow, this seems to be the solution indeed! I'll try it tomorrow and let you know what happend.

Thanks buddy 😉

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Answer 7

den.thed

Level 9

77,050 points

Sep 16, 2012 10:49 PM in response to Camarillo Brillo

Your welcome!

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Answer 8

LousyFool

Level 4

2,662 points

Sep 16, 2012 10:49 PM in response to Camarillo Brillo

I had the same trouble once, and formatting the external disk via Terminal fixed it. Here's how to:

In Disk Utility, mark the external disk and click on "Info". Note the name of the disk there, e.g. disk2s2.

Open Terminal (under Applications -> Utilities).

Enter the following string without quotes: "diskutil eraseDisk HFS+ newdisk disk2". (newdisk refers to the new name of the partition, you can choose a different name or change it later again in Disk Utility. disk2 is the name of the drive as per "Info", the s2 isn't necessary.)

Hit return and wait till the process is finished. The disk will be formatted even if locked before, and it will be available in Disk Utility again.

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Answer 9

Sep 17, 2012 6:39 AM in response to LousyFool

Dear LF,

thank you so much for the simplified steps (which I really needed)!

It worked like a charm!

Thanks to den.thed for his promplt reply and LF for helping me step-by-step.

You guys rock!

🙂

PS- I mistakenly hit the wrong button on your tip, LF: instead of "This solved my problem" I hit "This helped me".

Is there a way I can change that?

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Answer 10

LousyFool

Level 4

2,662 points

Sep 17, 2012 7:15 AM in response to Camarillo Brillo

You're welcome, and never mind the wrong click.

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Answer 11

den.thed

Level 9

77,050 points

Sep 17, 2012 4:27 PM in response to Camarillo Brillo

😉

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Answer 12

Greind

Level 1

0 points

Mar 29, 2014 3:27 AM in response to Camarillo Brillo

restart ur mac with the external plugged in..

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Answer 13

May 23, 2014 8:37 PM in response to Camarillo Brillo

Hello,

I ran across this post while attempting to set my old macbook to factory settings and was unable to erase the hard drive. I followed LFs advise and recieved the following message

Error: -10000: Could not unmount disk

Any advise on how to deal with this. I have no desire to keep any of the files on this drive (they were all migrated to my wifes new macbook).

Thank You

Volksplane

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Answer 14

Eric Root

Level 10

684,027 points

May 25, 2014 11:24 AM in response to volksplane

Are you booted into the Recovery volume or off a DVD? If you are trying to erase booted normally, you can't do that.

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Answer 15

zenjosso

Level 1

0 points

Aug 1, 2014 11:18 AM in response to LousyFool

Hi, I used this technique and got the following

Started erase on disk1

Unmounting disk

Error: -69877: Couldn't open device

Have you seen this before and could you help? You seem very knowledgeable 🙂

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