Luckyguide

You will have to backup your OS X partition to an external drive, boot from the external drive, use Disk Utility to repartition and reformat your hard drive back to a single volume, then restore your backup to the internal hard drive.

1. Access Hard Drive On Mac
2. Format Mac Hard Drive With Boot Camp Download
3. Format Mac Hard Drive With Boot Camp Download
4. Format Mac Hard Drive With Boot Camp Windows 10
5. How To Format Mac Drive

Feb 03, 2020 GUID Partition Map is appropriate for Mac disks. Master Boot Record is appropriate for external drives used with a PC or Boot Camp. If the partition map is not appropriate for the disk's intended use, click the Erase button or tab, then complete these items: Name: Enter a name that you want the disk to have after you erase it, such as Apple SSD.

1. Get an empty external hard drive and clone your internal drive to the external one.
2. Boot from the external hard drive.
3. Erase the internal hard drive.
4. Restore the external clone to the internal hard drive.

Clone the internal drive to the external drive

1. Open Disk Utility from the Utilities folder.
2. Select the destination volume from the left side list.
3. Click on the Restore tab in the DU main window.
4. Check the box labeled Erase destination.
5. Select the destination volume from the left side list and drag it to the Destination entry field.
6. Select the source volume from the left side list and drag it to the Source entry field.
7. Double-check you got it right, then click on the Restore button.

Destination means the external backup drive. Source means the internal startup drive.

Restart the computer and after the chime press and hold down the OPTION key until the boot manager appears. Select the icon for the external drive and click on the downward pointing arrow button.

After startup do the following:

Erase internal hard drive

1. Open Disk Utility in your Utilities folder.
2. After DU loads select your internal hard drive (this is the entry with the mfgr.'s ID and size) from the left side list. Note the SMART status of the drive in DU's status area. If it does not say 'Verified' then the drive is failing or has failed and will need replacing. SMART info will not be reported on external drives. Otherwise, click on the Partition tab in the DU main window.
3. Under the Volume Scheme heading set the number of partitions from the drop down menu to one. Set the format type to Mac OS Extended (Journaled.) Click on the Options button, set the partition scheme to GUID then click on the OK button. Click on the Partition button and wait until the process has completed. Do not quit Disk Utility.

Restore the clone to the internal hard drive

1. Select the destination volume from the left side list.
2. Click on the Restore tab in the DU main window.
3. Check the box labeled Erase destination.
4. Select the destination volume from the left side list and drag it to the Destination entry field.
5. Select the source volume from the left side list and drag it to the Source entry field.
6. Double-check you got it right, then click on the Restore button.

Destination means the internal hard drive. Source means the external startup drive.

Note that the Source and Destination drives are swapped for this last procedure.

Aug 28, 2012 1:35 PM

By Mike Wuerthele
Monday, January 29, 2018, 12:09 pm PT (03:09 pm ET)

Boot Camp will add a partition on-the-fly to your system drive, but there are some things that can stand in the way of that process. AppleInsider explains how to fix most of the issues preventing you from setting up that partition, if the assistant throws you the failure to partition error.


Pre-step. Get a backup with something other than Time Machine. For this task, we recommend Carbon Copy Cloner, SuperDuper, or ChronoSync to make a fully bootable, fully clone-able backup volume.
We've spoken about Carbon Copy Cloner and ChronoSync in the past. Before we go any further, it might be worth taking a look again.

Disable FileVault

Access Hard Drive On Mac

FileVault can, in some cases interfere with the partitioning process. Why, we're not sure, but the best and least destructive, way around it is to turn off Filevault, if it is on. If it isn't, then go to the next step.
Select System Preferences, and click Security and Privacy.

Click on the FileVault tab. Unlock the pane, validate your credentials, and click Turn Off FileVault.

Format Mac Hard Drive With Boot Camp Download

This isn't an immediate process. Decryption of your drive happens when the Mac is awake and plugged in. So, either use your Mac for a few hours doing things other than making a Boot Camp partition, or tell your Mac to never sleep in the Energy Saver control panel and walk away for a while.

Turn off Time Machine, un-associate any backup drives

You've got a backup, right? Don't proceed any further unless you have a backup that doesn't depend on Time Machine.
First, disassociate any backup drives with Time Machine. Select System Preferences

Format Mac Hard Drive With Boot Camp Download

, and click Time Machine.

Click Select Disk

Click on the drive being used as your Time Machine backup, and click Remove Disk. The Mac will pop up a dialog asking you to confirm that you want to do so.

Try to use Boot Camp assistant to partition the drive again. Should it still fail, you may need to remove Time Machine local snapshots as well.

Purge Time Machine local snapshots

Format Mac Hard Drive With Boot Camp Windows 10

For the tech saavy, the procedure to do this is different in High Sierra than it used to be. Apple killed a one-step, easy, Terminal process to turn off the feature, and automatically delete all local snapshots.
The procedure is still in the Terminal, though. Open the Terminal.

Enter tmutil thinlocalsnapshots / 9999999999999999
Depending on how many you have, and the speed of your drive, it may take a few moments to eradicate all the snapshots.

The above steps deal with most of the obstacles to a successful Boot Camp Assistant partitioning of your system drive. Once more, try to use Boot Camp Assistant to make the partition.
If all that still doesn't allow the partition to be created, then...

Format your hard drive

How To Format Mac Drive

If you've gotten this far, we're pretty confident of your ability to do this step. First, make sure you have a backup! Reformat your drive either by booting from your restore clone, or rebooting in recovery mode, and set up an APFS partition for your macOS install, and a macOS Extended (journaled) partition for what will become your Boot Camp partition later in the process.
Restore your backup to the APFS partition, run the Boot Camp Assistant again, and all should be well.