Can't partition (option greyed out) External HDD on Mac OS X El Capitan

I solved this issue by using Disk Utility by going up to the Menu bar, selecting "View", and selecting "Show All Devices". Then, the erase and partition buttons became active. I didn't have to get into Terminal at all.

Issue the following Terminal's command

diskutil erasedisk hfs+ External GPT /dev/disk2

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sundy_1 wrote:

Hi guys,

Scoured the net for an existing solution to this problem, but to no avail.

I'm attempting to partition a 500gb external HDD to run bootcamp, but whenever I go into Disk Utility, the option to partition the drive is greyed out.

I've previously erased and formatted to Mac OS X Journaled, so there's nothing on it, but still the partition option isn't available (see screenshot).

Any help is majorly appreciated. Thanks in advance!

This drive has been formatted as FAT (MS-DOS), for Microsoft. You have to erase it, to give it a new partition table. (GUID for OS X Journaled)

Leo

Your terminal output indicates that it has not been formatted correctly for HFS+

Make sure that you select the GUID partition and not the MBR which is for FAT. Thereafter your disk should be formatted correctly for HFS+

Leo

I have almost the same problem. My external HDD already has data and partition. First, the new Disk Utility interface threw me off. This is the new interface?

The HDD had 2 data partitions (160GB each), both of which I managed to erase. The third part is titled "BUFFALO Virtual CDrom Media" and has 0.8GB Uninitialised. It is an old HDD and I can't remember why it was set up like that. In all three (the two partitions as well as the Uninitialised portion), the partition is greyed out.

The other HDD I had, had two separate partitions, Backup 1 & 2, 1TB each. I erased Backup 1 but again the partition was greyed out and I am not able to further partition it or partition the entire HDD.

I tried the suggested Terminal command and got this:

Last login: Tue Jan 31 12:28:11 on ttys000

RobertscBookPro:~ robertxxx$ diskutil erasedisk hfs+ External GPT /dev/disk2

Started erase on disk2

Unmounting disk

Creating the partition map

Waiting for partitions to activate

Formatting disk2s2 as Mac OS Extended with name External

Initialized /dev/rdisk2s2 as a 465 GB case-insensitive HFS Plus volume

Mounting disk

Finished erase on disk2

RobertscBookPro:~ robertxxx$

To no avail, I still have the PARTITION icon dimmed.

This is the info of the external Samsung SSD T3

Volume name : External

Volume type : Physical Volume

BSD device node : disk2s2

Mount point : /Volumes/External

File system : Mac OS Extended

Connection : USB

Device tree path : IODeviceTree:/PCI0@0/XHC1@14

Writable : Yes

Is case-sensitive : No

File system UUID : 1B65CCC5-5FD0-34D9-AC1C-90C51234C0B0

Volume capacity : 499,763,888,128

Available space (Purgeable + Free) : 499,357,732,864

Purgeable space : 0

Free space : 499,357,732,864

Used space : 406,155,264

File count : 53

Owners enabled : Yes

Is encrypted : No

System Integrity Protection supported : No

Can be verified : Yes

Can be repaired : Yes

Bootable : No

Journaled : No

Disk number : 2

Partition number : 2

Media name :

Media type : Generic

Ejectable : Yes

Solid state : No

Parent disks : disk2

What can I do to partition the SSD?

Robert

Thank you so much and I wish I had found your answer yesterday! I spent so much time before finding your solution that worked. After following your instructions and pressing partition from the main listing of my hard drive in disk utilities, I got a message saying I needed to click the external option of my hard drive (which was the listing under the main hard drive) "file" and "enable journaling." After doing that the partition option was no longer greyed out and I was able to successfully partition the drive.

Hi guys, sorry for highjacking the post, but since the problem was already solved, I thought you wouldn't mind.

I had the same problem and used the command posted here on terminal, but still can't partition my external HDD. When I run diskutil list on my terminal, this is what I get now, after using the proposed hfs+ command:

Last login: Sun Mar 27 12:28:21 on ttys000

MacBook-Air:~ TT$ diskutil list

/dev/disk0 (internal, physical):

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *121.3 GB disk0

1: EFI EFI 209.7 MB disk0s1

2: Apple_CoreStorage Macintosh HD 120.5 GB disk0s2

3: Apple_Boot Recovery HD 650.0 MB disk0s3

/dev/disk1 (internal, virtual):

#: TYPE NAME SIZE IDENTIFIER

0: Apple_HFS Macintosh HD +120.1 GB disk1

Logical Volume on disk0s2

DE906773-3685-4883-A1E5-A0D123646512

Unencrypted

/dev/disk2 (external, physical):

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *1.0 TB disk2

1: EFI EFI 209.7 MB disk2s1

2: Microsoft Basic Data TT 999.9 GB disk2s2

MacBook-Air:~ TT$

Partition button is still greyed out. Any suggestions?

Thanks

This command deletes all of your data on your external hard drive if there's still content on it. So what I did was I used this, then I downloaded Stellar Phoenix Mac Data Recovery - instant download link <http://download.stellarinfo.com/StellarPhoenixMacDataRecovery.dmg.zip>. Run a scan and recover all the data that was on it 🙂🙂 so now you have a hard drive compatible with mac and windows, and still has all your files.

The fact the disk utility is now an abortion in comparison to its past incarnations, have to enter a command line to partition a disk? 3 disks in the machine now I have to enter another command to determine which disk identifier then cross my legs I don't screw everything up? - tell you what why dont I start using CPM again? that was a command line the whole point about macos is one GUI to rule them all, not a dumbed to do to uselessness heap, resorting to command lines is a failure apple I'm continuously disgusted with you nowadays F**ple, sierra is awful. disk utility in 10.4/10.5 was far superior this is ******** retrograde.