Having tried this before and rendered the mac partition unbootable, I decided to try again.
With help, I managed to retrieve my data, wipe the HDD and reinstall Mac OS Sierra via internet recovery. Now I am trying to reinstall Windows 10 and then Ubuntu 16.04 but am stuck at the first hurdle.
I tried to use Boot Camp assistant to create a new partition for Windows but was informed that Windows 10 is unsupported on this Mac (Windows 10 was previously running on this machine but I had updated from Windows 8.1). No problem, thought I, I'll just dig out the Windows 8.1 DVD... Same message as before: "Windows 10 cannot be installed on this Mac" eh? Not wishing to give up, I made a FAT partition using Disk Utility.
I then made another partition for the future Linux install. Feeling optimistic, I booted from the Windows 10 DVD in legacy mode and got to the point where you choose which partition to install Windows on. I keep getting the message "Windows cannot be installed on this partition" even when I format or delete the partition to leave free space.
Last time I "solved" this problem by booting in EFI mode and installing that way. This broke the partition map and left Mac OS unbootable.
What is the best way to install Windows on the partition without destroying the ability to boot Mac OS too? Really, I would like to then install Ubuntu on the other partition but one thing at a time...
I have read other posts on this topic but the solutions suggested do not seem to work in this situation.
Output from Diskutil list:
/dev/disk0 (internal, physical): #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *2.0 TB disk0 1: EFI EFI 209.7 MB disk0s1 2: Apple_HFS Mac OS 1.5 TB disk0s2 3: Apple_Boot Recovery HD 650.0 MB disk0s3 4: Microsoft Basic Data BOOTCAMP 514.0 GB disk0s4
The iMac has 8GB of RAM and I want the OSs to have roughly the space shown above. I have not started to install Linux yet and the Windows has failed to install so far.
OK so I have managed to install Windows 7 via bootcamp and then update to Windows 10, good so far, both OSs booting. Then I re-sized the Bootcamp partition from Windows to make space for Linux but guess what? The partition editor won't let me create a new partition in the unallocated space and Ubuntu won't install into it. I have already got 4 primary partitions and no more is possible. Still, I've got two OSs working again...I have updated the diskutil list and it doesn't show the resized windows partition. Is there any way of installing Linux in the free space without wrecking everything?
OK, so I went ahead and made 3 new partitions using Disk Utility and installed Ubuntu 16.04 onto them following instructions from Installing Ubuntu on Mac with macOS and Windows already installed Result: Mac and Ubuntu still boot fine but Windows now won't boot and gives a message " Missing Operating System" when I try to boot from it.
This is the new diskutil list output:
/dev/disk0 (internal, physical): #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *2.0 TB disk0 1: EFI EFI 209.7 MB disk0s1 2: Apple_HFS Mac OS 1.3 TB disk0s2 3: Apple_Boot Recovery HD 650.0 MB disk0s3 4: EFI 6.5 GB disk0s4 5: Linux Filesystem 198.7 GB disk0s5 6: Linux Swap 15.2 GB disk0s6 7: Microsoft Basic Data BOOTCAMP 514.0 GB disk0s7
Anyone got any ideas for how I can rescue the Windows install?