Adding additional internal drive for Windows?

2ms

macrumors 6502
Original poster
Nov 22, 2002
440
70
I just went through the hassle of buying a big SSD, taking apart my iMac, and replacing the HDD of my factory Fusion drive in hopes of being able to run Windows at high speeds via Bootcamp. But now I find that Mojave doesn't allow you to install Windows on a Fusion drive anymore. I had it once on an earlier version of OSX and it worked great except that Windows was slow because it was on the HDD.

Does anyone know if it would be possible to buy another damn SSD internal drive, put it in there alongside the other one I just installed, and have Bootcamp recognize it and allow me to install Windows?

Or rather is Bootcamp no longer possible on any Mac that has a Fusion drive? This is seriously annoying. Thanks for whatever help you could provide. Right now I have the factory 128GB PCIe drive and a 2TB Crucial SSD in place of the original HDD.
 

hfg

macrumors 68040
Dec 1, 2006
3,566
277
Cedar Rapids, IA. USA
You might un-fuse (after full backup) your custom Fusion drive ... then partition the large added SSD for the size you want for Windows. You can then re-fuse the Fusion drive using the remaining SSD space and the hard drive ... then restore your OS X installation to the Fusion drive. Then you can use BootCamp to install Windows to the now available SSD partition and you will have a speedy Windows installation. This will restore your large Fusion drive capacity if desired (hard disk could be external as an option (non-fusion recommended) using the other option below.

(This assumes you have an iMac model that can retain the hard disk, and replace the SSD with your larger purchased one).

OR

If you want to keep the 2 SSD drives in the iMac, don't Fusion them together! Install your OS X on the large SSD you added, and install Windows on the original 128GB SSD using one of the methods outlined in other threads on these forums.

Good luck ...
 
Last edited:

2ms

macrumors 6502
Original poster
Nov 22, 2002
440
70
You might un-fuse (after full backup) your custom Fusion drive ... then partition the large added SSD for the size you want for Windows. You can then re-fuse the Fusion drive using the remaining SSD space and the hard drive ... then restore your OS X installation to the Fusion drive. Then you can use BootCamp to install Windows to the now available SSD partition and you will have a speedy Windows installation. This will restore your large Fusion drive capacity if desired (hard disk could be external as an option (non-fusion recommended) using the other option below.

(This assumes you have an iMac model that can retain the hard disk, and replace the SSD with your larger purchased one).

OR

If you want to keep the 2 SSD drives in the iMac, don't Fusion them together! Install your OS X on the large SSD you added, and install Windows on the original 128GB SSD using one of the methods outlined in other threads on these forums.

Good luck ...
Thanks for the advice. Is it actually possible to fuse only part of a drive with another drive? I thought I tried that and the Fusion would only work on the entire drives.

The 128GB is too small for what I need to do with Windows.

Is it possible to add another SSD? Could I buy a two connector cable or something to enable that?
 

chabig

macrumors 603
Sep 6, 2002
6,034
3,272
Is it actually possible to fuse only part of a drive with another drive?
Yes it is. With APFS, you can create partitions of arbitrary sizes and combine them at will. See 'man diskutil' in terminal.

I don't think you can add extra drives inside the iMac. But why restrict yourself to inside. For $100 you can get a 500 GB Samsung external T5 SSD that simply plugs in. It's small, fast, and portable.
 
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Fishrrman

macrumors P6
Feb 20, 2009
17,405
5,637
OP:

You said that the internal factory-installed SSD is 128gb, right?
And you have installed a 2gb SATA SSD as well, right?

Your solution is this:
1. DE-fuse the fusion drive. Split the two drives into "standalone" drives.
2. Put the Mac OS onto the 128gb blade SSD (it is MUCH faster than the SATA drive)
3. Keep your Mac apps and basic account on the 128gb SSD as well
then...
4. PARTITION the 2tb SSD into two (or more) "pieces".
5. One should be Mac-formatted. Use that for the large libraries (movies, music, pics, large documents) that "won't fit" on the 128gb boot SSD. They will "live fine" there.
6. Install Windows on the second partition on the 2tb SSD. You may not even need BootCamp to do this.

My advice (but then, I "don't do Windows"):
I would NOT use BootCamp unless I absolutely, positively required "native Windows bootability".
Instead, I would use an "emulated solution" such as VMWare Fusion, Parallels, or the free "virtual box". Or perhaps even "Crossover" would work (it runs -some- Windows apps without having to install Windows).
 

hfg

macrumors 68040
Dec 1, 2006
3,566
277
Cedar Rapids, IA. USA
I would NOT use BootCamp unless I absolutely, positively required "native Windows bootability".
Instead, I would use an "emulated solution" such as VMWare Fusion, Parallels, or the free "virtual box". Or perhaps even "Crossover" would work (it runs -some- Windows apps without having to install Windows).
FWIW: If you do install Windows as a bootable OS ... with VMWare Fusion you can use that same installation as a virtual machine as well. No additional disk space required, and you can interactively use your Windows as either a VM or bootable for speed. Parallels may offer something similar, but I don't use that.
 

chabig

macrumors 603
Sep 6, 2002
6,034
3,272
If you do install Windows as a bootable OS ... with VMWare Fusion you can use that same installation as a virtual machine as well
Parallels can do the same. In my personal experience, I've decided that setting up Boot Camp isn't work the trouble for me. I appreciate the flexibility of having both environments running side by side without needing to reboot, not to mention that I don't have to dedicate a predefined amount of space to a Windows partition.
 
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2ms

macrumors 6502
Original poster
Nov 22, 2002
440
70
Yes it is. With APFS, you can create partitions of arbitrary sizes and combine them at will. See 'man diskutil' in terminal.

I don't think you can add extra drives inside the iMac. But why restrict yourself to inside. For $100 you can get a 500 GB Samsung external T5 SSD that simply plugs in. It's small, fast, and portable.
Thanks for the advice. I'm not getting anywhere here. When I try to create a partition it only allows me to do so within the small 128GB drive. The other 2TB seem to be greyed/cross-hatched out in the pie diagram.

Then when I try to un-fuse the Fusion drive as directed on this page, the diskutil cs list command only returns a message: "No CoreStorage logical volume groups found" rather than any UUID so I might delete volumes.

Argh!
 

2ms

macrumors 6502
Original poster
Nov 22, 2002
440
70
OP:

You said that the internal factory-installed SSD is 128gb, right?
And you have installed a 2gb SATA SSD as well, right?

Your solution is this:
1. DE-fuse the fusion drive. Split the two drives into "standalone" drives.
2. Put the Mac OS onto the 128gb blade SSD (it is MUCH faster than the SATA drive)
3. Keep your Mac apps and basic account on the 128gb SSD as well
then...
4. PARTITION the 2tb SSD into two (or more) "pieces".
5. One should be Mac-formatted. Use that for the large libraries (movies, music, pics, large documents) that "won't fit" on the 128gb boot SSD. They will "live fine" there.
6. Install Windows on the second partition on the 2tb SSD. You may not even need BootCamp to do this.

My advice (but then, I "don't do Windows"):
I would NOT use BootCamp unless I absolutely, positively required "native Windows bootability".
Instead, I would use an "emulated solution" such as VMWare Fusion, Parallels, or the free "virtual box". Or perhaps even "Crossover" would work (it runs -some- Windows apps without having to install Windows).
I am using Windows to run CAD software, which needs some performance. Would Fusion slow it down noticeably? I would prefer to always have Mac running. But I do need performance and rock-solid stability. I have no idea how to do the rest of what you recommend, though I appreciate your listing it. Do you know if there is a guide or something somewhere on how to do all that?
 

HelpMePls

macrumors newbie
Apr 19, 2019
20
0
How’d you go with this? I just tried the same as you and failed thus far: