I Can't GULD format my HD

offtheroad

macrumors regular
Original poster
Jun 14, 2007
183
1
Albuquerque, New Mexico
I can't do a GUID format my internal HD with Yosemite. It says It can't unmount the HD to do it but it did let me do "Erase Free Space" but not a basic erase. So How can I make my internal HD bootable?Will that happen when I install Yosemite automatically
Error Msg:
Volume Erase failed Could't unmount disk
 

thefredelement

macrumors 65816
Apr 10, 2012
1,142
558
New York
I can't do a GUID format my internal HD with Yosemite. It says It can't unmount the HD to do it but it did let me do "Erase Free Space" but not a basic erase. So How can I make my internal HD bootable?Will that happen when I install Yosemite automatically
Error Msg:
Volume Erase failed Could't unmount disk
Are you running disk utility from the drive you want to format? I don't think that can be done.

If you have a USB stick, put the 10.10 installer on it and then boot from it, then you can manipulate your internal drives as much as you want.

I used this guide before for the terminal commands because I never remember them: http://www.macworld.com/article/2367748/how-to-make-a-bootable-os-x-10-10-yosemite-install-drive.html
 

offtheroad

macrumors regular
Original poster
Jun 14, 2007
183
1
Albuquerque, New Mexico
Can format my internal HD GuID

No I'm working from another internal HD. Thanks for your reply. I check out the link. I have an early 2009 Mac Pro
I do the partiction the way your link says but at the end when I say apply I get the error msg:
"Partition failed with error:
Couldn't unmount disk
 
Last edited:

IowaLynn

macrumors 65816
Feb 22, 2015
1,306
288
Try from Recovery Mode.

And when you install Yosemite, that will be from running the installer from a USB drive or something or not? Booting from the installer (and pull and keep all your other drives off line).

What is on the drive you wanted to format (erase, using Partition tab) that might be being accessed?

Click on the raw top level of the drive (as in "WDxxxxx") or change the number of partitions and use the OPTIONS button which should be highlighted, and the next window select the type (GUID/GPT, MBR, APR).
 

offtheroad

macrumors regular
Original poster
Jun 14, 2007
183
1
Albuquerque, New Mexico
Can.t unmount internal HD

This is the name of the HD 1TB SAMSUNG HD103SJ Media I have Yosemite installer on my desktop and are you saying to unmount all other internal HD's while I try again to Partition the other drive. well unmounting other internal's didn't help.
 

thefredelement

macrumors 65816
Apr 10, 2012
1,142
558
New York
This is the name of the HD 1TB SAMSUNG HD103SJ Media I have Yosemite installer on my desktop and are you saying to unmount all other internal HD's while I try again to Partition the other drive. well unmounting other internal's didn't help.
Can you try it from Recovery?

I still suggest using a USB disk w/an OS X Installer for disk utility stuff when changing partitions.
 

offtheroad

macrumors regular
Original poster
Jun 14, 2007
183
1
Albuquerque, New Mexico
Can you try it from Recovery?

I still suggest using a USB disk w/an OS X Installer for disk utility stuff when changing partitions.
What is Recovery and I have Yosemite Installer on a DVD and also on the desktop. The internal HD I'm trying to get ready to install YOSEMITE has been emptyed by me dragging all to the trash and doing a "erase free space" because disk utility wouldn't do a normal erase because of the error msg. And no I haven't tried to install YOSEMITE yet but I have successfully installed it on other internal HD's without problems.
 

thefredelement

macrumors 65816
Apr 10, 2012
1,142
558
New York
What is Recovery and I have Yosemite Installer on a DVD and also on the desktop. The internal HD I'm trying to get ready to install YOSEMITE has been emptyed by me dragging all to the trash and doing a "erase free space" because disk utility wouldn't do a normal erase because of the error msg. And no I haven't tried to install YOSEMITE yet but I have successfully installed it on other internal HD's without problems.
If you have it on a DVD, insert the DVD and boot from it, then choose disk utility from the menu after the installer loads. Don't go to just install 10.10 right away, go to tools, then disk utility and do what you want to the drive, then install it if that's what you want to do.
 

IowaLynn

macrumors 65816
Feb 22, 2015
1,306
288
If you have it on a DVD, insert the DVD and boot from it, then choose disk utility from the menu after the installer loads. Don't go to just install 10.10 right away, go to tools, then disk utility and do what you want to the drive, then install it if that's what you want to do.
It is so easy to use either a USB flash drive, or even just set aside a small hdd partition that you can use and be faster and easier. With DVDs so often they fail, and seemed to be harder to get one working. Also I had to use 16GB flash drive but dual layer DVD I guess works.

Was the DVD created with http://liondiskmaker.com/ ? Now supports Yosemite
 

ApfelKuchen

macrumors 68040
Aug 28, 2012
3,142
1,804
Between the coasts
Is this a new drive, or has it been previously used to boot OS X? If it's a new drive, I'm not sure why this is happening.

If it has been used to boot OS X 10.7.x Lion or any newer version of OS X, then it contains two partitions - Macintosh HD, and a hidden OS X Recovery partition. This explains OS X Recovery: https://support.apple.com/en-us/HT4718 Rather than erase the entire HD (1TB SAMSUNG HD103SJ Media), erase only the Macintosh HD partition.
 

offtheroad

macrumors regular
Original poster
Jun 14, 2007
183
1
Albuquerque, New Mexico
password on newly installed Yosemite won't work

I just installed yosemite to internal HD and I can log in with my password but can't unlock anything else with it. I have installed many other internal HD's and use the same name and PW but now there's a problem? If I go into Pref's and try changing it in the Users & Groups it don't help. Thanks