Why can't I erase HD with Disk Utility?

nhuser wrote:

I have a MBAir 11" with Mavericks. I want to erase the HD. I go to Disk Utlity>choose Macintosh HD>Erase. All choices are greyed-out (Format, Name, Erase Free Space, Security Options, Erase). I can't choose anything. What am I missing?

You can't do it while the system is booted. Hold down Command and R whilst restarting and use DiscUtility from there. You will be in your recovery partition.

Cheers

Pete

Restart the computer with the Command and R keys held down and erase it from the recovery partition.

The active startup disk can't be erased. The Erase Free Space and Security Options functions aren't available for SSDs.

(96554)

Click here and see the note at the bottom of the article.

(96558)

I Also had this problem. Even when I tried rebooting into recovery mode. You may have to unlock the drive before if it is encrypted. When I installed 10.10 it asked if I wanted to encrypt, so I did. To unencrypt just boot into recovery mode (cmd+r on boot up) then select disk utility. Click on the greyed out drive. Go to file at the top. Then press unlock. It shouldn't be greyed out anymore. 🙂

Hi guys,

Made a time machine copy on a 500gb external hard drive of my 13" MBP with a HDD currently in it.

Then took my 500gb SSD from an old 15" MBP, removed the HDD and put it in my 13" MBP.

Opened up 13" MBP in restore mode. Chose restore from time machine back up.

Choose the time machine external drive as source. Then chose the SSD drive to restore to.

Said it was erasing the drive... Asked for a password...

I typed in my usual password. It then said the SSD drive couldn't be erased.

Took the SSD out and put the original HDD back in.

Plugged the SSD into a firewire 800 caddy to try erase it in disk utility as an external.

This drive will show up in disk utility but the erase option isn't available.

I can repair the disk but it says the disk is perfectly fine.

I can click on the partition option but everything is greyed out and I can't partition it at all.

This drive will now no longer show up on the desktop or finder.

This is driving me crazy!

Just want to erase the SSD, use time machine to restore onto it and get busy.

Please help!

Thanks,

Chris

Please post the output of diskutil list from OS X terminal when the SSD in the FW enclosure is connected to Mac.

Hi Loner T,

Here is what I get.

I'll also put a picture up of what I'm seeing in disk utility...

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *500.1 GB disk0

1: EFI EFI 209.7 MB disk0s1

2: Apple_CoreStorage 499.2 GB disk0s2

3: Apple_Boot Recovery HD 650.0 MB disk0s3

/dev/disk1

#: TYPE NAME SIZE IDENTIFIER

0: Apple_HFS Untitled *498.9 GB disk1

Logical Volume on disk0s2

4306F405-E4CD-46A4-A31E-7D7BC1199F32

Unencrypted

/dev/disk2

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *500.1 GB disk2

1: EFI EFI 209.7 MB disk2s1

2: Apple_CoreStorage 499.1 GB disk2s2

3: Apple_Boot Recovery HD 784.2 MB disk2s3

Chris-Prendergasts-MacBook-Pro:~ chrisprendergast$

Please be careful with images, where your personal information may show up.

This is a known issue with Yosemite Disk Utility. It does not deal with CoreStorage volumes correctly and falls over itself. The safest method I know off is using OS X Terminal and diskutil commands. The tool-tip when you hover your mouse over the SSD shows that it has become a CoreStorage volume. The other issue with DU is that whenever it sees an SSD and HDD combination, it wants to convert to a CoreStorage volume. DU will provide an error messages about "fix"ing disks. If you do not "ignore" it, it will "fix" disks and convert them to CoreStorage.

Please post the output of diskutil cs list and I can give you exact commands to use. You also cut off the heading of diskutil list (which should have /dev/disk0 some where).

You need to boot using command+Opt+R (Internet Recovery - not local Recovery with Command+R) to be able to erase your internal drive.

Do you want to erase both your Internal HD and SSD? or just the SSD?

Hi Loner T,

I'll post a picture of both terminal read outs, without anything missing.

What I'd like to do is format the SSD, put it in my mac and use an existing external drive with a time machine backup & restore to the SSD.

As I said before, everything was going smoothly until I got the error message, 'disk could not be erased' during a time machine restore.

Thanks,

Chris

I cannot see your second image. Can you post a link via an external image sharing website?

Loner T,

Info here:

https://www.dropbox.com/sh/rem6qsjf9r5qlhp/AABpb539eF0fZAZrf-ZaAogXa?dl=0

Thanks