Combine Partitions back together

Question

Level 1

8 points

Combine Partitions back together

I thought I would install windows on a separate partition using Boot Camp assistant but it all went horribly wrong somehow and I am now left with two partions on my hard drive. One is Apple_HFS MacIntosh HD and the other Apple_Boot Recovery HD. Is their anyway I can combine these partitions back together.? The smaller partion is not seen by Finder so I have about 50Gig space which I cant use. I'm using High Sierra 10.13.4 with 16gig ram on a mac mini (late2012) 2.5GHz Intel core i5.

Posted on May 11, 2018 2:48 AM

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Answer 1

Loner T

Level 9

59,536 points

May 15, 2018 12:09 PM in response to polyfony

You want to merge the Recovery HD into macOS, not the other way. The command should be

diskutil mergePartitions jhfs+ "Macintosh HD" disk0s2 disk0s3

The order of the disks is critical.

If you re-install macOS after the mergePartitions, it will only update the macOS files, and rebuild the Recovery HD.

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Answer 2

Lanny

Level 6

13,225 points

May 13, 2018 1:59 AM in response to polyfony

If you previously added a Boot-Camp partition, the only way to remove it properly is to use the Boot-Camp configuration Utility. The same utility that you used to create the Boot-Camp Partition in the first place.

Don't use Disk Utility for this purpose.

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Answer 3

Loner T

Level 9

59,536 points

May 13, 2018 1:59 AM in response to polyfony

Bootcamp Assistant failed to properly merge the partition back into the macOS partition and left the space in Recovery HD - now 48GB. This is a known issue in High Sierra. Do you have a Time Machine backup of macOS?

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Answer 4

Lanny

Level 6

13,225 points

May 13, 2018 6:21 AM in response to Loner T

Bootcamp Assistant failed to properly merge the partition back into the macOS partition and left the space in Recovery HD - now 48GB. This is a known issue in High Sierra. Do you have a Time Machine backup of macOS?

It's more likely that the OP used Disk Utility instead of the Bootcamp Assistant.

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Answer 5

Loner T

Level 9

59,536 points

May 13, 2018 5:03 AM in response to polyfony

There is another method, but it means losing your local Recovery HD temporarily. Can you check if you boot into Local Recovery using Command+R during boot? If you see a spinning globe and/or are prompted for your wireless password, you are in Internet Recovery.

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Answer 6

Loner T

Level 9

59,536 points

May 13, 2018 6:27 AM in response to Lanny

Lanny wrote:

Bootcamp Assistant failed to properly merge the partition back into the macOS partition and left the space in Recovery HD - now 48GB. This is a known issue in High Sierra. Do you have a Time Machine backup of macOS?

It's more likely that the OP used Disk Utility instead of the Bootcamp Assistant.

See as examples.

Can't use partition after deleting Bootcamp

Bootcamp not create windows partition in OS 10.13

iMac storage issue

I had created a Bug Report - 35249393 - which Apple Engineers decided not to pursue.

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Answer 7

sterling r

Community Specialist

May 11, 2018 3:46 PM in response to polyfony

Hello polyfony,

I understand that you have a question on combining partitions. I use my device a lot and know how important it is to have your device running smoothly. I'm here to help.

Here is a resource that can assist you:

Disk Utility Help

Specifically:

You can erase all volumes on a device and create new ones. For example, if you want to change the partition map of a USB, Thunderbolt, or other storage device from Master Boot Record to GUID Partition Map. If you simply want to erase a volume, see Erase a volume.

WARNING: Erasing and partitioning a device destroys all data on all volumes of the device.

Choose View > Show All Devices.

Select the device in the sidebar you want to erase and repartition, then click the Erase button .

Note: You can’t erase the device that contains your startup volume.

Enter a name for the initial volume.

Click the Map pop-up menu, then choose a format for the initial partition.

For MS-DOS and ExFAT partitions, the name must be eleven characters or less.

GUID Partition Map: Used for all Intel-based Mac computers.

Master Boot Record: Used for Windows partitions that will be formatted as MS-DOS (FAT) or ExFAT.

Apple Partition Map: Used for compatibility with older PowerPC-based Mac computers.

Click Erase, then click Done.

Have a great day!

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Answer 8

Loner T

Level 9

59,536 points

May 13, 2018 3:48 PM in response to polyfony

What we want to do is

Install macOS on an external disk, so it gets its own local Recovery HD
merge the internal disk's Recovery HD into macOS
re-install macOS from the external disk on the internal disk, to rebuild the correct sized Recovery HD

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Answer 9

polyfony Author

Level 1

8 points

May 12, 2018 12:50 AM in response to Lanny

Thanks to sterling r and Lanny for the advice.

I am a wee bit confused. If I use the diskutility app it only shows one partition of about 450gid on the 500gig hard drive, but if I use diskutil through the terminal it shows both partitions as shown below:

/dev/disk0 (internal, physical):

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *500.1 GB disk0

1: EFI EFI 209.7 MB disk0s1

2: Apple_HFS Macintosh HD 451.2 GB disk0s2

3: Apple_Boot Recovery HD 48.7 GB disk0s3

I want to recombine disk0s2 and disk0s3 so that I can use the space. I looked at boot camp assistant but I cant see how I can recombine the partions using this. Any advice?

Thanks

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Answer 10

polyfony Author

Level 1

8 points

May 13, 2018 2:00 AM in response to Loner T

Loner T thanks for your reply. Now I can understand what has happened.

I don't have a Time Machine backup of macOS, I only backup my data to Dropbox and update the OS whenever Apple sends out updates. So I'm not very keen on doing something where I might loose data. Alternatively could I get the OS to see this partition in Finder and make the partition usable? I can live without the 50 gig but I would prefer to make it usable.

Thanks again for your help

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Answer 11

polyfony Author

Level 1

8 points

May 13, 2018 11:57 AM in response to Loner T

I tried booting using Command + R and and a window with MAC OS Utilities appeared containing the apps Time Machine, OS recovery over internet, Disk Utility, and one other (which i forgot to take a note of 😝). I could also access the Terminal from the top menu. Clicking on Disk Utility shows the 450Gb partins and a Disk Image OS X Base System of about 2GB. Using Disk Util from the terminal shows lots of other disk images.

If I use OS recovery over the internet will this enable me to recombine the two partions? I should say my mac mini works fine with as it is and one would not know there was another partion on the disk since performance seems unaffected.

Thanks

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Answer 12

polyfony Author

Level 1

8 points

May 15, 2018 12:04 PM in response to Loner T

Looks relatively simple. Can you just confirm that the second and third steps won't affect any other data on the hard drive i.e. I won't loose anything from My Documents, Photos etc.

Thanks again for your help

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