USB partition for Mac

USB partition for Mac

Trying to partition my usb on my Mac. I’ve tried everything and no access to a PC.
I tried MS-DOS (FAT) with 2 partitions &
tried the Mac OS Extended (Journaled) and GUID Partition map for my 32 GB thumb drive. Then when i get to the partitioning step I select "MS-DOS(FAT)" for each partition but no luck.
Anyone have success on their Mac? I’m using disk utility on Mojave. I’ve tried different disks also.
Operation failed...

gmr6415 | 28 October 2018

In the Mac OS disk utility program selecting MS-DOS(FAT) formats the drive to FAT(32). To check after formatting go into your finder window, select the USB drive and hit the command and "I" keys at the same time. The pop up will show you it's FAT32. When formatting make security options are set to "fastest". Anything else and you are encrypting the drive.

If you can't format it at all I click on the first aid tab and run "repair disk" on it.

gmr6415 | 28 October 2018

I forgot to mention that some USB drives don't allow partitioning. If in the partitioning tab the MS-DOS FAT is grayed out your drive may not be partitionable.

Try using the erase tab, set up a single partition and see if that works first.

david_gelfand | 28 October 2018

If you have Drive Genius for Mac, try it. Current version is 5.2.2, I think. It has the advantage of being able to partition “on the fly” I.e. not necessary to erase what’s already on the disk & I have found it woks well with SSDs as well as spinning discs or with Mac GUID SanDisk 128gb thumb flash drives. I haven’t tried yet to reformat my 64gb Fat32 SanDisk micro thumb drive that I use for CDs. Hope this helps a little. Anyone try DG5 for this purpose?

moz1058 | 28 October 2018

Thank you, David. I will certainly try DG5. I will try anything at this point; even going to Best Buy to use their PC. :)

creativeguy | 28 October 2018

Disk Utility works fine. You need to set the partition map to Master Boot Record, and then choose FAT 32 formatting.

bradbomb | 28 October 2018

It needs to be Master Boot record for Partition map not GUID

quadriceps | 28 October 2018

I had the same failures but was successful using diskutil in terminal.

moz1058 | 29 October 2018

Solved: After MUCH trial and error, with ya'lls help, this worked for me on Mojave:
1. Open Terminal and type: diskutil partitionDisk /dev/disk2 2 GPT ExFAT Volume1 50% ExFAT Volume2 R
2. Open DiskUtility
3. "View" on the top toolbar
4. Show all devices
Then I had a partition that would not mount...
5. Erase disk2s3 with the ExFAT format

BOOM, it worked...Sheeeeeesh

Hope I am able to save some folks some time and stress

quadriceps | 29 October 2018

diskutil partitionDisk disk2 2 GPT FAT32 MUSIC 80% FAT32 TESLACAM 20%

Be sure to load up some FLAC 96/24 or higher, I recommend Sgt. Pepper's Deluxe Anniversary Ed. to start.

moz1058 | 29 October 2018

Quadriceps for the win...That worked in one simple step. Thank you so much!!!!!! My 5 steps ended up not showing up in my car today. You saved the day!!!!!!!

jwins | 29 October 2018

Thanks for all this info, folks. Will jump into this shortly. Here's a related question: All my music, at this point, is in iTunes, some of which I've add via CDs or purchases over the years, a lot of which I've downloaded from Apple Music. I can see how to copy files over that have an M4A extension, but what about everything else? Suggestions greatly appreciated!

CorkChop | 29 October 2018

@gmr6415 Anything but fastest and you’re ”encrypting the drive”? Um, that not what it’s doing.

“Fastest” deletes the index to the files but leaves the files untouched. It is possible that the files can be recovered. That’s not the same as encrypting the drive.

andyjcrane | 31 January 2019

Ok, I tried everything listed above on my Sandisk Ultra 3.0 128gb. Nothing worked! Disk Genius does not support the drive. The terminal says "You cannot manually partition an existing APFS Container disk" The Disk Utility will not allow me to select partition. I erased the disk, unmounted, restored... none would allow the partition function. Please help!

srredbeard | 16 March 2019

I highly recommend adding one step before using the command quadriceps gave to partition the USB.
At the command prompt type: diskutil list This will allow you to verify which disk number was assigned to the USB. You might not like the results above if the computer didn't mount the USB as disk2.

dwharrison | 10 April 2019

Just used quadricep's command to do my USB. One additional tip if that doesn't work for you (e.g. andyjcrane) is that you may want to use Disk Utility fo erase the whole USB key to FAT32 first, and then use the command line tool to do the partitioning. That worked for me.

a9838464 | 29 July 2019

1. Plug the drive into a USB socket (if you have a recent MacBook or MacBook Pro that only has USB-C connectors, you’ll need a USB-C to USB-A adaptor).

2. Open a new Finder window and click on the drive. Make sure it has no files on it that you need. The process of reformatting it will wipe all the data from it.

3. Once you’ve copied any files you need from the USB drive to your Mac, go to Applications>Utilities and double-click on Disk Utility.

4. Click on the USB drive in the sidebar and then choose Erase from the toolbar at the top of the window.

5. In the window that drops down type a name for the formatted drive in the box next to Name.

6. Choose a format from the dropdown menu.

7. If you have previously stored sensitive data on the drive, click the Security tab.

8. Choose a security level using the slider. The further to the right you move the slider, the more ‘passes’ the erase tool will make and the more securely files will be deleted. However, it also increases the time it takes to format the drive quite considerably.

9. Click Ok then click Erase.

Tip: You don’t need to erase a whole drive to delete files securely. If you have confidential files or sensitive data you need to remove from your Mac completely, you should use iMymac’s File Shredder. It’s specifically designed to securely delete sensitive data and will render it unrecoverable.

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