Cannot partion drive, Mac El Capitan, option greyed out

WD External Drives External Drives for Mac
1

Help !

Purchased a new WD drive on the weekend with the intention of using it as a time machine & general drive. I was able to connect the drive & reformat to Mac HFS with extended journaling. However, when I try to select the create partition option in disk utility the option is greyed out & cannot be selected.
The drive can be used & accessed & even works as a time machine backup, however a partition cannot be created. I have re-formatted a few times & even formated back to windows format & back to mac.

Looking at diskutil it appears that the issue is the drive is stuck as an “FDisk_partition_scheme” not GUID as required for El Capitan to partiion the drive.

Does anyone know how to fix this & change the partition scheme on the drive ?

dev/disk1 (external, physical):
#: TYPE NAME SIZE IDENTIFIER
0: FDisk_partition_scheme *4.0 TB disk1
1: Apple_HFS External HD 4.0 TB disk1s

Thanks !
bmac

2

Are you unable to click the Options button in the partition tab in order to change it to GUID Partition Table?

3

Thanks for the reply
The actual partition tab is greyed out & does not allow me to access the partion tab at all.

4

Which external hard drive do you have? Is it a RAID unit?

5

No basic WD Elements 4tb

6

Found the solution on the apple support site
from terminal
diskutil erasedisk hfs+ External GPT /dev/[diskname]

[diskname] is the higher level disk in disk utility, (the one with the manufacturers name)

After running this and going back into disk utility I was able to access the partion button after enabling journaling from the file menu

7

Hi bmac!

I have the same problem but when I go into terminal and enter “diskutil erasedisk hfs+ External GPT /dev/[diskname]” - my diskname being WD Passport … it still doesnt work.

Any suggestions would be most welcome. I have been struggling for 4 hours and I fear I may not have a macbook to work on soon due to its accidental fall out the window…

Thank you in advance
Margaret

8

Hi Margaret,
Sorry i don’t have any other suggestions, i think i lucked out by trying out this solution i found on applesupport

Good luck !

9

Thank you bmac, worked like a charm!