Installing windows 10 on a particular setup

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Level 1

8 points

Installing windows 10 on a particular setup

Hello everyone,

I am thinking of installing Windows10 via Bootcamp on a partition on my iMac. I already tried this yesterday and after waiting a legendary amount of time (3hrs 30 minutes) for the disk to be partitioned, when I reached the point during the w10 install where it asks to choose the partition where you want to install it, Windows refused to install on the Bootcamp partition with the message: "We couldn't create a new partition or locate an existing one".

After googling for a bit I saw that this might/is happening because of external drives connected via USB.

Now, getting to the 'particular setup' part of my question: i have an iMac 21,5 which came by default with a 1TB / 5400rpm HDD. So , since having a 5400 rpm disk on a computer nowadays seems to me like self-mutilation (thanks Apple), I decided to buy an external SSD and to move everything there and keep the internal disk as ...storage. So, here is where my problem is when it comes to 'removing all USB external drives' : since I am booting on it and using it as main disk, I can't really do that.

Also after bootcamp failed to install windows, he also reset my booting order and it booted on the internal drive - luckily I didnt format it or anything so i guess it still had the required OS stuff on it.

So my questions would be:

1. Does anyone have any safe suggestions on how to install windows while booting from the external ssd and keeping it plugged in?

2. I was thinking to remove the SSD and boot on the old internal drive and try to install with Bootcamp from there but i am wondering: would this possibly cause problems afterwards when I want to boot again from my external SSD?

Thanks in advance !

iMac

Posted on Mar 4, 2018 2:15 AM

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Answer 1

Loner T

Level 9

59,471 points

Mar 4, 2018 4:34 AM in response to nivde

Disconnect the external SSD
Boot from the internal disk
Run SMC and NVRAM reset
- How to reset the System Management Controller (SMC) on your Mac - Apple Support
- How to reset NVRAM on your Mac - Apple Support
Use BC Assistant to install Windows on the internal disk
After Windows is fully functional, connect SSD
Reboot and use Alt/Option key to choose from
- Internal disk macOS
- External disk macOS
- Internal disk Windows

Keep the internal installation intact, so you can boot into macOS, if there is an 'emergency' or you need Software Updates. What year is the iMac?

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Answer 2

Loner T

Level 9

59,471 points

Mar 4, 2018 6:56 AM in response to nivde

Since you already have Sierra on the internal disk, boot from it, disconnect the external HS SSD, and install Windows. Once it is functional, you do not need to deal with HS BCA issues, and can keep the all three OSes.

If you keep a mix of HS and S, I recommend not manipulating partitions or running BCA from HS. If you need to, boot from Sierra and do what is necessary.

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Answer 3

nivde Author

Level 1

8 points

Mar 4, 2018 2:58 AM in response to CountryGirl56

I want to install it on the internal drive, but I want to be able to do this while booting macOS from the external SSD (which is at the moment my main drive). Also, as i specified I would not mind booting from the internal one , installing windows in it, and then coming back to my current setup - but I do not know if the risk of losing the capability to boot afterwards from the SSD is high or low.

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Answer 4

nivde Author

Level 1

8 points

Mar 4, 2018 5:05 AM in response to Loner T

Thanks LonerT for the detailed answer.

The iMac is late 2015.

One question: although i am not planning on doing anything to the internal installation, just for my curiosity why wouldnt I be able to boot from the ssd in case of an 'emergency' ?

Also, i recently upgraded to HIgh Sierra on the SSD ... that leaves the itnernal instalation to Sierra (if i remember correctly the version it had on it); can this be an issue?

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Answer 5

Loner T

Level 9

59,471 points

Mar 4, 2018 7:11 AM in response to nivde

nivde wrote:

One question: although i am not planning on doing anything to the internal installation, just for my curiosity why wouldnt I be able to boot from the ssd in case of an 'emergency' ?

In most cases, an external boot disk will work. If you have physical port-related issue on your Mac, then external disks can be problematic. External enclosures do not support boot ability consistently, which can cause failures. Depending on the enclosure, booting can also be slow, if the connection is a USB2 connection. The internal disks generally boot faster. A USB3 becomes comparable to a SATA3 connection, but a TB disk becomes faster for external boot than USB3.

nivde wrote:

Also, i recently upgraded to HIgh Sierra on the SSD ... that leaves the itnernal instalation to Sierra (if i remember correctly the version it had on it); can this be an issue?

High Sierra has a new file system called APFS. Currently it applies to only internal SSD/Flash disks, and does not impact Fusion drives (yet!). Unless you absolutely must have different versions, it is better to have the same macOS version (patches to the same level) on an external boot device as the internal disk, otherwise software incompatibility can lead to unpredictable results. BCA is one such piece of software. BCA on HS has more issues than BCA on Sierra, partly due to immature support for the new APFS system. It has more bugs. My recommendation is to stay on Sierra on both external and internal disks.

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Answer 6

nivde Author

Level 1

8 points

Mar 4, 2018 6:23 AM in response to Loner T

The external ssd is a GDRIVE 512 usb 3.0 . macOS loads a lot faster from the external SSD, that's why I chose to stay on it (and bought it in the first place 🙂 ). What do you mean by 'a TB disk' ? Terrabyte?

My internal disk is not a fusion disk. Its a plane old 1TB 5400 hard drive (the standard from Apple for my iMac at that time). Regarding speeds, I dont think there's anything slower than it 😀

I dont need to have separate versions, the thing is I don't even plan on ever booting on the internal disk, except in a case of emergency like you said. As far as having the same OS on both disks, I'd rather upgrade Sierra to HS than downgrade HS from the SSD ( I dont even know how to do that but probably there is a way).

Regarding BCA and your recommandation, I have two questions:

1. If neither of my disks were upgradedd to APFS ( the internal probably wasnt because I didn't install HS on it) and the external wasn't either because it's external - does this lower / remove the risks of BCA failing?

2. If my decision would be not to downgrade to S from HS, based on your recommandation I am thinking best way is to cancel the windows installation - or at least postpone it for later?

Thanks once again for your detailed answers and support 🙂

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Answer 7

Loner T

Level 9

59,471 points

Mar 4, 2018 7:11 AM in response to nivde

TB is Thunderbolt. Versions 1,2 and 3 just increase the over speed and throughput. USBc/TB3 can be confusing though.

Your 2015 iMac can also support Fusion drives, so adding an internal SSD is possible. DIY can be a challenge, but an AASP or Apple can upgrade it, giving you better performance.

Even if you do not have APFS on your Mac, HS BCA is not as bug-free as the Sierra version. You can boot from the internal disk's Local Recovery using Command+R, and re-install Sierra on the external SSD.

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Answer 8

nivde Author

Level 1

8 points

Mar 4, 2018 6:46 AM in response to Loner T

Oh , Thunderbolt. Didn't think of that. Thanks.

Regarding an upgrade, I remember asking at the Apple Store here where I live if I can upgrade it, and they said no. Even if the disk will break, they will replace it with the same 5400 snail. Though I am not 100% sure if I didn't say that I wanted them to replace it with a SSD that i bought myself. Been a while , can't remember.

I know DIY is quite a challenge that's why I opted for the external SSD.

Maybe I'll recheck with the Apple Store just in case.

Regarding Sierra - if I have to chose between not installing windows OR downgrading to Sierra, I think I'll chose to not install windows as i said. May sound silly but I upgraded to HS in order to be able to play a game on Steam which required HS. And actually all this fuss about installing windows is because I am having issues with a Logitech g29 steering wheel and some mac games - problems which seem to not be present when i tested on a Windows / Parallels environment.

But just in case I DO go crazy and reinstall Sierra on the SSD ...will it keep my data? Or erase everything?

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Answer 9

nivde Author

Level 1

8 points

Mar 4, 2018 7:10 AM in response to Loner T

I already did a repartioning with HS BCAyesterday when I was trying to install Windows but since it didnt work I used BCA to restore the disk to one partition ( it was the only option available om BCA after the failed windows attempt)

Think that might have caused issues ?

I will try what you suggested in your last post.

Really appreciate all the detailed information and taking your time to explain stuff !

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Answer 10

nivde Author

Level 1

8 points

Mar 10, 2018 10:06 AM in response to Loner T

Sorry for the delay I decided to wait until the next weekend to have time available in case smth messed up.

I launched Sierra with the ssd disconnected but I forgot ( or better said did not think it through ) that I deleted all Applications from the old disk and recently the whole contents of my user folder ( to free up space since i am using that disk mostly for storage nowadays).

So although I can boot into Sierra now, i get only question marks icons on the dockbar and there s no bootcamp assistant or anything else - which makes sense having done what I did :)

I was thinking to restore sierra from the recovery option BUT I am not sure if :

1. this will leave my data intact on the drive ( i have plenty of stuff on it saved)

2. will this affect in any way the ability to boot from the ssd ? maybe delete some low level boot settings or smth . I would DEFINITELY not want losing this :)

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Answer 11

nivde Author

Level 1

8 points

Mar 11, 2018 8:34 AM in response to Loner T

Soooo, did a restore on the old drive - seems I had El Capitan when I got the iMac ...so restored that, upgraded to Sierra...then used BCA to install Windows...installed Windows...tested a bit...then plugged back in the SSD with HS and ALT-Booted to choose it...so far everything works great . Hope it will stay this way, wasted half of day on all this 😀

Thanks a lot Loner T for all the help !

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