Windows 10 install and fusion drives

Question

Level 1

5 points

Windows 10 install and fusion drives

For the past two weeks, I've been trying to install a fresh copy of the Windows 10 Anniversary Update ISO that Microsoft advises you use to install Windows on a Mac with Bootcamp. And so far, I have been unsuccessful.

For the record for the past year or so, my late-2013 27" iMac has had Windows 10 installed and had been working fine until a couple of weeks ago when a game I was running crashed. Soon after that, Windows started to run really slowly to the point where I needed to force a shutdown and try to repair Windows, but to no avail. At the point, the slowness seemed to be affecting my computer's OS X side as well. I eventually ended up doing a fresh install of OS X through the Internet Recovery.

Most of the time, Boot Camp Assistant seems to do its job, making the USB2 flash drive ready for Windows installation and partitioning out space for Windows on my 3TB fusion drive. Once my iMac restarts, it, I assume, loads into the EFI installation of Windows 10. I skip the Windows key question because I don't have one at the moment, but I don't think that matters too much, assuming I'll be able to purchase a key later and activate the OS once it's loaded. Unfortunately, I haven't been able to get the installation to get all the way to actually loading Windows, making an account and logging in. Most of the time, after close to two hours sometimes, the installer gets stuck on "Getting Ready" or loops back to the screen where you can customize settings after waiting 30+ minutes in the "Just a moment ..." screen after picking the customizable options.

I've removed and have tried to reinstall Windows 10 with Bootcamp at least 15 times so far, and I've noticed the installation process goes really slow every time. I've tried the normal Bootcamp way that Apple advises by just clicking the format button on the Bootcamp pation, and I've tried deleting the Bootcamp partition in the Windows installer and just choosing the unallocated space for the installation. I've also tried formatting the partition using diskpart in the command line during the installation. Nothing seems to speed up the install. I've also tried installing through the non-EFI way through the USB, but get an error because the GPT of the Fusion Drive. I've also been pretty vigilant about resetting the PRAM each time, but I feel I may have forgotten to do that between some attempted reinstalls.

I'm currently reinstalling OS X yet again. Once that's done I'm going to reset the PRAM and SMC and then try to use Boot Camp Assistant one more time, following the instructions listed on Apple's site here. I have a feeling the same thing will happen where the install will slow to a crawl and get stuck at the usual spots (Getting Ready or looping around the customize settings portion).

I don't think the issue is my hard drive. Disk Utility doesn't output any errors when I do first aid on it, Sierra seems to work just fine on it.

Should I try to find an original Windows 10 ISO somewhere? It looks like it's not available anywhere here, which is what Apple's Boot Camp guide links you to. I only see the Creators and Anniversary updates as downloadable ISOs for Macs. I only ask because I think I've seen some Boot Camp guides mention that you shouldn't install Windows 10 update versions, but I have a feeling that's outdated because Windows is suggesting to install Anniversary Update, and there's no option to download an OG Windows 10 ISO.

I seem to remember when I successfully installed Windows 10 the first time, I installed through the non-EFI way, but that would require an MBR drive, I think. My Fusion Drive is GUID. And I don't think there's a way to make one partition on a drive MBR while leaving the other partitions as GPT. And I could just be confusing myself and probably did it through EFI.

I've tried and tried and am starting to run out of things I can think of to try to get Windows 10 back up and running on my iMac. Any help, tips or suggestions would be greatly appreciated!

iMac (27-inch, Late 2013), macOS Sierra (10.12.6), 3TB fusion drive

Posted on Sep 24, 2017 12:15 PM

Reply

Answer 1

Loner T

Level 9

59,536 points

Sep 24, 2017 7:36 PM in response to MistoPixo

MistoPixo wrote:

About 90 percent of these attempts have been through the EFI Boot, I'd say. So, if this trick I found here, doesn't make a difference, I will try creating a hybrid MBR.

The initial parts of the video do not mention Macs. Also, you are not installing Windows on the SSD part of the fusion drive, but on the HDD part as shown by the location of the BC partition on the 3TB HDD.

MistoPixo wrote:

Is there a guide to create a hybrid MBR drive? Or do I just copy the commands in your terminal block? sudo fdisk /dev/disk0 and so on? Will the creation of this hybrid MBR drive delete the contents/format the fusion drive?

See the rebuild MBR section of Re: El Capitan has deleted my bootcamp windows partition . You need GPT Fdisk - GPT fdisk download | SourceForge.net . A hybrid MBR with the current partition layout will not work, since the Hybrid MBR cannot map addresses beyond 2TB.

There are two possible layouts on a 3TB (or larger) Fusion drive on the HDD part. We do not touch the SSD part at all, otherwise it can get even more problematic.

macOS Part 1 + Windows + macOS Part 2 such that Windows starts within the first 2TB addresses on disk and is less than 1TB, or,
macOS Part 1 + Windows (>1TB) which also forces the Windows disk addresses to start within the first 2TB.

Newer versions of macOS BC Assistant (Sierra) erroneously assume that the Mac can support EFI universally, which is incorrect, because Macs older than late 2013 models only support BIOS, but Sierra is supported on some of these models and makes a complete hash of Fusion drives, and worse on 3TB Fusion drives.

Reply

Answer 2

Loner T

Level 9

59,536 points

Sep 25, 2017 1:29 AM in response to MistoPixo

EFI Installs are 'faster' during boot in most cases. They are also cleaner, because there is less emulation, normally accomplished using a CSM-BIOS layer.

You can create a >1TB partition using BC Assistant without any issues. To get EFI to install correctly, instead o fetch default BIOS method, two manual steps are required.

manually choosing the EFI Boot using Alt/Option key, and,
re-formatting the designated partition as Free Space, instead of FAT32. This can be done using Shift+F10 using Diskpart commands when the Windows installer is running

Reply

Answer 3

MistoPixo Author

Level 1

5 points

Sep 24, 2017 12:27 PM in response to MistoPixo

Would rebuilding the fusion drive using diskutil in Internet Recovery terminal cause any problems/slowness for the Windows 10 installation? I've had to rebuild my fusion drive a few times because of bad Windows installations (or bad decisions I made during the attempted installation) made it so I couldn't remove a partition with Boot Camp Assistant.

Reply

Answer 4

Loner T

Level 9

59,536 points

Sep 24, 2017 6:54 PM in response to MistoPixo

Your late 2013 Mac supports both EFI and BIOS installations. BIOS installations require a Hybrid MBR (overlay on a GPT disk).

Here is an example.

sudo fdisk /dev/disk0

Password:

Disk: /dev/disk0 geometry: 62260/255/63 [1000215216 sectors]

Signature: 0xAA55

Starting Ending

#: id cyl hd sec - cyl hd sec [ start - size]

------------------------------------------------------------------------

1: EE 0 0 2 - 25 127 14 [ 1 - 409639] <Unknown ID>

2: AF 25 127 15 - 1023 250 4 [ 409640 - 742676624] HFS+

3: AB 1023 250 5 - 1023 1 27 [ 743086264 - 1269536] Darwin Boot

*4: 07 1023 2 5 - 1023 121 5 [ 744355840 - 255858688] HPFS/QNX/AUX

sudo gpt -vv -r show /dev/disk0

gpt show: /dev/disk0: mediasize=512110190592; sectorsize=512; blocks=1000215216

gpt show: /dev/disk0: Suspicious MBR at sector 0

gpt show: /dev/disk0: Pri GPT at sector 1

gpt show: /dev/disk0: Sec GPT at sector 1000215215

start size index contents

0 1 MBR

1 1 Pri GPT header

2 32 Pri GPT table

34 6

40 409600 1 GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B

409640 742676624 2 GPT part - 48465300-0000-11AA-AA11-00306543ECAC

743086264 1269536 3 GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC

744355800 40

744355840 255858688 4 GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7

1000214528 655

1000215183 32 Sec GPT table

1000215215 1 Sec GPT header

The current partition layout will not support BIOS mode. It can support EFI, if you manually select EFI Boot from the USB Installer. On an iMac, every failure must be followed by a NVRAM and SMC Reset.

Reply

Answer 5

MistoPixo Author

Level 1

5 points

Sep 24, 2017 7:14 PM in response to Loner T

About 90 percent of these attempts have been through the EFI Boot, I'd say. So, if this trick I found here, doesn't make a difference, I will try creating a hybrid MBR.

Is there a guide to create a hybrid MBR drive? Or do I just copy the commands in your terminal block? sudo fdisk /dev/disk0 and so on? Will the creation of this hybrid MBR drive delete the contents/format the fusion drive?

Reply

Answer 6

MistoPixo Author

Level 1

5 points

Sep 24, 2017 10:47 PM in response to Loner T

Thank you. I have to take my iMac in to get its hinge fixed tomorrow and probably won't get it back until Thursday at the earliest. I'll have to try this out when I get it back.

Is there anything else you can think of that I could try to get the EFI to install or do you think I need to stick with the hybrid MBR, considering the iMac I'm working with?

My Fusion Drive is back in one 3+TB partition for now.

If I do end up with having to go the hybrid MBR way, I think I'd prefer to do:

macOS Part 1 + Windows (>1TB) which also forces the Windows disk addresses to start within the first 2TB.

Does this mean the Windows partition should be the second partition, and it will have to be larger than 1TB? Do I go through Boot Camp Assistant to set up these partitions? Or, do I do all of this through Terminal/GPT Fdisk? I'll definitely try to fully understand your guide before I get my iMac back.

I assume once these are set up, I try to install through the non-EFI way, using the WINSTALL USB drive Boot Camp Assistant creates using the Anniversary Update ISO.

As for the SSD, how do I make sure I don't touch the SSD part at all when going through the GPT Fdisk commands?

Sorry for my confusion, this hybrid MBR seems a little intimidating to me, but I think this may have been how I got Windows installed on my machine in the first place, but I could be wrong. It's been a while since I was able to successfully install Windows on my iMac through Boot Camp. The fact that my MacOS became really slow at the same time when Windows 10 crashed on me and started acting really slowly, makes me think the Windows partition was set up this way initially, but I'm just guessing here.

Reply

Answer 7

MistoPixo Author

Level 1

5 points

Sep 25, 2017 8:16 PM in response to Loner T

Well, I think I know what the problem is.

I took my iMac in to a Simply Mac store to get its hinge replaced and, in the process of a diagnostic test, they discovered the HDD of the 3TB Fusion Drive has bad sectors and is failing. SSD appeared to be fine (Maybe that's what was keeping my MacOS side of the iMac from crashing?). The person who checked me in told me there was a program Apple was a part of to replace specific 3TB Fusion Drives for free.

I think this is a story about the program.

I wasn't contacted about or recall ever hearing about this program, or else I would have taken it in much earlier because of the potential problems. And I ran first aid through DiskUtility many times during the process of installing Windows 10 recently after the initial crash and saw no problems listed each time and would always turn out successful, which led me to believe my Fusion Drive wasn't the issue.

Apparently I bought my iMac within the 3-year window to get the Fusion Drive replaced for free. I'll need to call up Apple tomorrow and hope they understand the situation and can help me out.

Thanks for all your help. Here's to hoping everything goes swimmingly.

Reply

Answer 8

Loner T

Level 9

59,536 points

Sep 26, 2017 3:34 AM in response to MistoPixo

The specific recall program link is no longer available, but you can take a look at Apple Launches 27" iMac 3TB Hard Drive Replacement Program . Apple will most likely honor the program and replace it. Please back up macOS before you take it to the Apple Store or an AASP.

Reply