Unable to access neither Partition Layout nor Option tab in Partition tab on Disk Utility
core-storageguidpartition
I have a problem that I cannot select Option tab in Partition tab as shown in above screenshot. I wanted to convert my external hard disk to GUID partition table.
Thank you in advance for your help.
Best Answer
You can't partition disk1 freely because it contains a Core Storage Volume Group (disk1s2 -> disk2).
You can revert to a non-CoreStorage by booting to Macintosh HD (disk0s2) and opening Terminal.
Enter the following to get all necessary infos:
diskutil cs list
Example listing:
CoreStorage logical volume groups (1 found)
|
+-- Logical Volume Group A629E051-D7B0-4B8C-A803-074F62704636
=========================================================
Name: System
Status: Online
Size: 53946696192 B (53.9 GB)
Free Space: 16777216 B (16.8 MB)
|
+-< Physical Volume 90C09FC0-4215-4871-901B-70E2C9C7D464
| ----------------------------------------------------
| Index: 0
| Disk: disk0s2
| Status: Online
| Size: 53946696192 B (53.9 GB)
|
+-> Logical Volume Family F6962E38-50E4-4458-BFE6-CF2E179352F5
----------------------------------------------------------
Encryption Status: Unlocked
Encryption Type: None
Conversion Status: NoConversion
Conversion Direction: -none-
Has Encrypted Extents: No
Fully Secure: No
Passphrase Required: No
|
+-> Logical Volume BD36C73D-860D-4DC6-B125-AD624F448B88
---------------------------------------------------
Disk: disk2
Status: Online
Size (Total): 53496696192 B (53.5 GB)
Conversion Progress: -none-
Revertible: Yes (no decryption required)
LV Name: System
Volume Name: System
Content Hint: Apple_HFS
This is done the same way with external or internal drives.
Start your Disk Utility (Applications -> Utilities -> Disk Utility). In the left pane, select the disk for which you wish to change the partition table (select the disk, not one of its partitions, disks are at the "top levels" in the tree view in the left pane).
In the right pane, select the "Partition" tab. You must repartition your drive in order to change to GUID, so in the "Partition Layout" dropbox select "1 partition" (or however many you want).
Click on the "Options..." button right below the list view showing your partitions and select "GUID partition table". Adjust your partitions as needed and hit "Apply".
Here are instructions for undoing a Core Storage conversion (source - this method worked for me). It should be non-destructive, but as always, take a backup first!
Boot into Recovery HD. If for any reason you don't have Recovery HD, then you'll have to make a bootable Yosemite drive and boot into that.
In the Menu Bar, select Utilities > Terminal.
Run diskutil cs list. You'll get an output that looks like this (credits to the Ask Different user in my source):
Select your Logical Volume ID (the one highlighted in the screenshot) and copy it to the clipboard.
Run the Terminal command diskutil cs revert Paste-Your-Logical-Volume-ID-Here.
Run diskutil cs list to verify that your computer can't find any CS volumes.
You're done! Now Disk Utility should be able to do everything you need it to do to your HD!
Best Answer
You can't partition disk1 freely because it contains a Core Storage Volume Group (disk1s2 -> disk2).
You can revert to a non-CoreStorage by booting to Macintosh HD (disk0s2) and opening Terminal.
Enter the following to get all necessary infos:
Example listing:
If your Logical Volume is revertible enter:
(lvUUID is the UUID of the Logical Volume)
with the UUID of the example above
If the Logical Volume is encrypted you have to enter a passphrase.
After the conversion repartition the drive as needed.
If the LV isn't revertible you have to copy the content of the volume 21Tech to another volume and delete the Logical Volume Group with:
(lvgUUID is the UUID of the Logical Volume Group)
with the UUID of the example above
Then repartition the drive as needed.