Catalina - Unable to Install Bootcamp

Question

Level 1

90 points

Catalina - Unable to Install Bootcamp

The HDD in my wife's Late 2013 27" iMac began to fail. Original build is Fusion Drive - 128GB SSD + 1TB HDD. I replaced the failing Seagate 1TB HDD with a 1TB Samsung EVO 860.

Based on recommendations elsewhere before I installed the new 1TB SSD I effectively split the Fusion drive by separating the 128GB SSD from the HDD. Now there are two drives listed: 128GB Apple SSD and 1TB Samsung SSD.

I performed a clean install of macOS Mojave (as that was the most recent OS loaded) on the Samsung 1TB SSD. After installing fresh copies of all of the applications, transferring all of the files, etc. I updated it to Catalina and it runs quite well.

As there are a few Windows applications she would like to run I thought I'd install Windows 10 via Bootcamp on the unused 128GB SSD.

Unfortunately I've run into a number of Bootcamp Assistant errors, all involving the creation of a USB installation disk. I've properly formatted and tried several 64GB or larger USB 3.0 thumb drives in different USB ports. Either BCA indicates it can't read the drive, the drive is too small or midway the attempt fails with an error saying that the activity couldn't be completed.

All of the issues arise prior to even attempting to use the "spare" 128GB drive as a Windows boot disk.

I've tried the same steps on my Late 2017 27" iMac (also Fusion drive) running Mojave and it works fine. I'm wondering if this is a Catalina issue or...?

I've searched here and elsewhere but not found any threads that match the issues I'm experiencing. Any advice would be appreciated.

TIA!

iMac (27-inch Late 2013)

3.5GHz Quad-Core Intel Core i7

32GB 1600MHz DDR3

NVIDIA GeForce GTX 780M 4GB

macOS Catalina v10.15

iMac Line (2012 and Later)

Posted on Oct 28, 2019 2:22 PM

Reply

Answer 1

Top-ranking reply

Loner T

Level 9

59,526 points

Oct 28, 2019 4:22 PM in response to richsadams

richsadams wrote:

Here is a copy of the current disk lists:

My recommendation is re-building the Fusion drive on the 2013 iMac. You need to treat the EVO as the HDD. Be aware that EVO Firmware may create new issues even in proper Fusion configuration.

Reply

Answer 2

Loner T

Level 9

59,526 points

Oct 29, 2019 4:33 AM in response to richsadams

richsadams wrote:

Forgot to ask... I've read in more than one place that creating a Fusion Drive with two SSD isn't a good idea (and why I separated them initially). Is that still the case?

No. It is a myth promoted to bolster the 'Fusion' concept a bit. There are no known issues with two SSDs in a Fusion drive. In the previous incarnation of Fusion (CoreStorage), you can have more than two disks in a Fusion configuration. This allows the CS engine to use the faster 'secondary' disks to move blocks around.

Also, you mentioned that there could be other issues after recreating the Fusion Drive? Is that specific to the Samsung EVO or in general.

It is specific to a Samsung EVO.

Again, I probably won't fix it since it's not broken overall, but I might want to make use of the 128GB drive someday.

The fix is fairly straightforward. Backup via Time Machine, rebuild Fusion, Restore via TM. See Can't upgrade to Mojave on iMac with … - Apple Community as an example.

Reply

Answer 3

Loner T

Level 9

59,526 points

Oct 28, 2019 4:20 PM in response to richsadams

richsadams wrote:

Based on recommendations elsewhere before I installed the new 1TB SSD I effectively split the Fusion drive by separating the 128GB SSD from the HDD. Now there are two drives listed: 128GB Apple SSD and 1TB Samsung SSD.

This will stop BC Assistant from working and installing Windows will not work.

Unfortunately I've run into a number of Bootcamp Assistant errors, all involving the creation of a USB installation disk.

This is expected outcome of a 'split' Fusion drive.

All of the issues arise prior to even attempting to use the "spare" 128GB drive as a Windows boot disk.

BC Assistant does not support this configuration.

I've tried the same steps on my Late 2017 27" iMac (also Fusion drive) running Mojave and it works fine. I'm wondering if this is a Catalina issue or...?

If your Fusion drive is intact, it will work correctly. It will also work on the 2013, if the Fusion drive is rebuilt.

Reply

Answer 4

richsadams Author

Level 1

90 points

Oct 28, 2019 9:17 PM in response to richsadams

Thanks also for that.

Since the machine is working very well I think I'll opt to just leave it as-is. I don't want to introduce new issues.

We also have an almost new MacBook Air so I think I'll add Bootcamp to it instead. That should keep the wife happy. ;)

Thanks again!

Reply

Answer 5

richsadams Author

Level 1

90 points

Oct 28, 2019 9:23 PM in response to Loner T

Forgot to ask... I've read in more than one place that creating a Fusion Drive with two SSD isn't a good idea (and why I separated them initially). Is that still the case?

Also, you mentioned that there could be other issues after recreating the Fusion Drive? Is that specific to the Samsung EVO or in general.

Again, I probably won't fix it since it's not broken overall, but I might want to make use of the 128GB drive someday.

TIA!

Reply

Answer 6

Loner T

Level 9

59,526 points

Oct 29, 2019 4:38 AM in response to richsadams

richsadams wrote:

We also have an almost new MacBook Air so I think I'll add Bootcamp to it instead. That should keep the wife happy. ;)

Happy Wife, Happy Life (quoting Robbie Koenig - Tennis commentator).

Reply

Answer 7

richsadams Author

Level 1

90 points

Oct 29, 2019 11:33 AM in response to Loner T

Awesome info... thanks so much!

I ended up loading Windows 10 on the MacBook... and in doing so put on my mad scientist hat, installing it on an external SSD (256GB) thumb drive, using WintoUSB, a Windows 10 iso and a downloaded copy of the Bootcamp support files. It works great and it doesn't take up any space on the MacBook's SSD! It even accepted a key from a copy of Windows 7 Ultimate that I had to activate it. Sweet.

I was tinkering with the idea of recreating the Fusion Drive. I usually create a clone with SuperDuper but it appears that Catalina has thrown them for a loop. They have a beta that's supposed to work, but it doesn't. Sent them a support request so we'll see what happens. In the meantime it's currently backing up to Arq Cloud and once that's done I'll create a TM backup and maybe give the FD recreation a go.

I'll be sure and post back.

Thanks again! 👍

Reply