1

MacBook Air 2015, Mojave installed, 125 GB flashdrive

We had a VM for windows, but with installing Mojave, deleted everything additional down to bare Mac OS and tried to install W10 with boot camp assistant (BCA). According disk utility, MacOS is taking 27 gb (including W10 iso file), free 93 gb. BCA partition keeps 47 gb for Mac, with remark 8 gb free. It will not go lower.

I used Disk Utility to make a disk partition of 30 gb for Mac, 90 gb for second partition. No problem. I deleted that partition, again disk space 120 gb, free 93. Tried again BCA, no dice, will not go below the 47 gb for Mac OS.

Any way to push this lower? I would like to go 85 gb for W10, 35 gb for Mac. That should be enough for both OS and some working space for extra programs, all larger data files go through external drives or cloud.

Update: Output from 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_APFS Container disk2           30.0 GB   disk0s2
   3:                Apple_APFS Container disk1           75.0 GB   disk0s3
   4:      Microsoft Basic Data Data                      15.9 GB   disk0s4 

/dev/disk1 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +75.0 GB    disk1
                                 Physical Store disk0s3
   1:                APFS Volume W10                     745.5 KB   disk1s1

/dev/disk2 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +30.0 GB    disk2
                                 Physical Store disk0s2
   1:                APFS Volume Macintosh HD            20.5 GB    disk2s1
   2:                APFS Volume Preboot                 44.4 MB    disk2s2
   3:                APFS Volume Recovery                522.7 MB   disk2s3
   4:                APFS Volume VM                      1.1 GB     disk2s4
David Anderson
  • 40,244
McDuff
  • 11

1 Answers1

2

If the BCA will not create the partitions in a way you want and you can, then consider installing W10 using a flash drive. While the use of a flash drive is not required, the procedure is simplified when one is employed. A Microsoft recommended install of W10 involves creating 3 new partitions which are listed below.

  • A Microsoft Reserved (MSR) partition of about 16 MB.
  • A Windows partition of at least 20 GB.
  • A recovery tools partition (WRE) of about 800 MB.

Even though Microsoft recommends a MSR, often the Boot Camp Assistant does not create this partition and Windows apparently works correctly when omitted. If the WRE partition is not created, then the software normally installed in this partition will be installed in the Windows partition. So technically, you only need the Windows partition. You can manually create the other partitions, but again this complicates the installation procedure. The exact Microsoft document explaining these requirements can be found at the Microsoft website UEFI/GPT-based hard drive partitions. Note: This document states the WRE should be 500 MB, but with the current W10 release, the size needs to be 800 MB. So, if you wish to create the three partitions, then the procedure would be as follows.

  1. Boot from the flash drive.
  2. When the first Windows 10 installation screen appears, enter a shift+F10 to open a Command Prompt window.
  3. Run the diskpart command to create the partitions. In other words, create free space by deleting the single partition you created using macOS and create the three partitions in the free space.
  4. Close the Command Prompt windows an proceed with the installation of Windows.

Instructions for creating a USB Windows 10 installer flash drive can be found as part of the accepted answer to Boot Camp Assistant fails to create the USB installer from the Windows 10 October 2018 Update.

Note: When installing using a flash drive, the Mac may reboot back to macOS before Windows finishes installing. If this happens, the select Windows from the "Startup Disk" pane of the "System Preferences" application, then click on the "Restart" button. The Windows installation process will pick up from where it left off.

Steps to Download the Windows Support Software

This example as done using a iMac (21.5-inch, Late 2013) running macOS Mojave Version 10.14.4.

  1. Using the Finder application, open the Applications folder. Next, open the Utilities folder, which can be found in the Application folder.
  2. Open the Boot Camp Assistant, which can be found in the Utilities folder.

  3. From the menu bar, select Action, then Download Windows Support Software.

  4. In the popup window, select where to store the download. In the image shown below, the Downloads folder was selected.

  5. Below is an image of what to expect during the download.

  6. Below is an image of what is shown when downloading completes. Some of the Windows Support Software files may be needed during the installation of Windows. Therefore, even though you are suppose to run the Windows Support Software application (Setup.exe) after installing Windows, you still need to copy this software to the same flash drive containing the Windows ISO files.

Installing Without the Windows Recovery Environment (WRE) Partition

Note: You probably can skip step 2.

  1. Boot from the Windows 10 flash drive.

  2. In this case, you will not need to use the diskpart command. However, you still could use the diskpart command to view the partitioning of the drives. When the image below appears, press the key combination shift+F10 to open a Command Prompt Window.

    Enter the following commands.

    diskpart
list disk
select disk 0
list partition
list volume
exit

    Your results should be similar to what is shown in the image below.

    Note: The output from list disk command must show a * in the Gpt column for Disk 0.

    After entering the exit command to close the Command Prompt window, proceed with the installation.

  3. If you encounter the image shown below, select Custom: Install Windows only (advanced).

  4. When the image shown below appears, select Drive 0 Partition 3.

  5. Confirm the selected partition is approximately 75 GB. Next, click on the Delete button, then click on the OK button in the popup window.

  6. When the image shown below appears, select Drive 0 Unallocated Space.

  7. Confirm the selected unallocated space is approximately 75 GB. Next, click on the New button, then click on the Apply button. Click on the OK button in the popup window.

  8. The result should appear similar to what is shown below. Confirm the selected partition is approximately 75 GB. Click on the Next button to continue with the installation of Windows.

    Note: If you do not what a Microsoft Reserved (MSR) partition, then you can delete the partition before proceeding. In this example, I did not delete this partition.

David Anderson
  • 40,244
  • I have a 16 gb flash drive which has the W10 IOS file and one other folder. Format of the drive is NTSF. Trying to boot into the flash drive (using option key during restart) but the Macbook only showed the Mac drive, not the flash drive. – McDuff May 04 '19 at 18:35
  • I have a 16 gb usb drive which has the W10 ISO file and one other folder with over 3 GB in data. Format of the drive is NTSF. Trying to boot into the flash drive (using option key during restart) but the Macbook only showed the Mac drive, not the flash drive. The ISO I downloaded from the MS VLSC; we have a 6 licenses for our non-profit. UPDATE - I reformatted the usb drive to exFAT but I cannot get the windows support software for making the usb drive bootable. Boot camp assistant does not give a download option. Am I missing something? – McDuff May 04 '19 at 19:23
  • Mojave version 10.14.4 (18E266) – McDuff May 04 '19 at 20:01
  • The Boot Camp Assistant does allow you to just download the Windows Support Software. Select "Action" from the menu bar at the top of the screen. See my updated answer. – David Anderson May 04 '19 at 20:20
  • You do realize that you must mount the Windows ISO file, then copy the files contained in the ISO to the flash drive. Likewise, you must open the WindowsSupport folder and copy the files contained in the folder to the flash drive. The flash drive should be ExFAT formatted using the Master Boot Record scheme. – David Anderson May 04 '19 at 20:41
  • OK, not used to Macs enough. I did not see that menu bar because it is not on the BCA pop-up window but on the top menu bar. Took some time to figure that out. Now downloading, will follow the steps and report back when all is ok or not. Thanks so far – McDuff May 04 '19 at 20:53
  • All downloaded and the USB drive is ready. Will continue tomorrow, its midnight now here. Thanks so far. – McDuff May 04 '19 at 21:56
  • USB boot works, now partition is a problem. Decided to skip W10 three partitions, and do all in the single partition. First try, with DiskPart after USB boot, I did not see what I expected to see, and did not want to mess up the main Mac OS. So with disk utility made a partition, could not find it with DiskPart, spent a lot of time getting to delete the partition but managed. – McDuff May 05 '19 at 14:15
  • In the fresh full Mac drive, I managed to make two partitions: windows 74 gb and then Data 16 gb. Both formatted as exFAT (trying to be smart without too much knowledge). Bootup in USB drive, DiskPart sees only the Data volume, nothing else. Back to utility, turns out that the W10 partition now suddenly shows up as APSF. Definitely NOT as I had made it. Now disk utility -showing all devices- shows container 1 with Mac OS volume in APSF, container 2 with empty volume called W10 also in APSF, and a volume called Data, without being in a container, as exFAT. What did I do wrong? – McDuff May 05 '19 at 14:16
  • It would be best if you could post the output from the command diskutil list to your question. What is the purpose of the 16 GB partition? I assume you want to keep this partition. – David Anderson May 05 '19 at 16:35
  • The 16 gb data partition in exFAT format is supposed to be a data section that both W10 and Mac can access and is easy to synchronise to our other computers. Diskpart list I will try this afternoon. – McDuff May 06 '19 at 07:13
  • your afternoon or my afternoon? BTW, the command is diskutil list and you enter the command in a macOS Terminal application window. – David Anderson May 06 '19 at 07:58
  • back online shortly, was on the road for projects – McDuff May 07 '19 at 20:57
  • ....... 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_APFS Container disk2 30.0 GB disk0s2 3: Apple_APFS Container disk1 75.0 GB disk0s3 4: Microsoft Basic Data Data 15.9 GB disk0s4 – McDuff May 07 '19 at 21:00
  • part 2. /dev/disk1 (synthesized): #: TYPE NAME SIZE IDENTIFIER 0: APFS Container Scheme - +75.0 GB disk1 Physical Store disk0s3 1: APFS Volume W10 745.5 KB disk1s1 – McDuff May 07 '19 at 21:03
  • part 3-last. /dev/disk2 (synthesized): #: TYPE NAME SIZE IDENTIFIER 0: APFS Container Scheme - +30.0 GB disk2 Physical Store disk0s2 1: APFS Volume Macintosh HD 20.5 GB disk2s1 2: APFS Volume Preboot 44.4 MB disk2s2 3: APFS Volume Recovery 522.7 MB disk2s3 4: APFS Volume VM 1.1 GB disk2s4

    ..... $

     – McDuff May 07 '19 at 21:03
  • how it is readable, don't know how to make a nice copy-quote preserving the list structure. – McDuff May 07 '19 at 21:04
  • Its close to midnight again here, I will try continue with this tomorrow during morning and early afternoon (my time) – McDuff May 07 '19 at 21:22
  • You can go ahead and follow the instructions in the section with the title: Installing Without the Windows Recovery Environment (WRE) Partition – David Anderson May 08 '19 at 08:19
  • Seems to work, but I did not complete because some GB are missing. I checked with diskpart as said list disk shows disk 0 online 113 GB, disk 1 no media, disk 2 online 14 GB. LIST PARTITION on disk 0 lists P1-system size 220 MB offset 20 KB, P2-unknown size 27 GB offset 200 MB P3 unknown size 69 GB offset 28 GB P4-primary size 14 GB offset 98 GB. – McDuff May 08 '19 at 10:49
  • Continuing: LIST VOLUME V0 - letter C label Data fs exFAT type partition size 14 GB status healthy. V1 - no ltr EFI FAT32 partition 200 mb healthy hidden. V2 - E label none fs non removable 0 B no media. V3 D Robo exFAT removable 14 GB healthy. Probably the "Robo" is the volume with the missing GBs but I have really no idea where that Robo one is coming from, since my last report on partitioning few days ago I did not do any partitioning or made changes, neither in mac Terminal or disk utility nor in W10 diskpart. – McDuff May 08 '19 at 10:58
  • Everything looks OK. You can proceed to step 3. Your Windows 10 installation USB flash drive has the label Robo. In the example, I used the label WINSTALL. It does not matter if the labels are different. I did not realize you would have 3 disks. The only important disk is Disk 0 and so far this disk looks OK. – David Anderson May 08 '19 at 18:08
  • Ooops, should have seen that. Just installed W10. all seems to work although the partition size is still 69,9 GB instead of close to 75 GB. For now, I will check on that late rthis week and will start install programs and see how it works out. – McDuff May 08 '19 at 21:25
  • Anyway, your help is greatly appreciated and I finally worked through this frustration. If you ever come to the Czech Republic, I owe you a beer or two. – McDuff May 08 '19 at 21:26