Contribute
Register

Dual booting on two separate m.2 drives

Joined
Nov 18, 2015
Messages
115
Motherboard
Gigabyte Z390 Designare
CPU
i9-9900K
Graphics
RX 580
Can you disable either or both of the M.2 slots in the UEFI/BIOS?
I have not been able, until today, to find information about this possibility or to find options available in the UEFI/BIOS menus (Gigabyte Z390 Designate F6 - latest version).
Can there be the problem that the installation of Windows 10 (or Linux) - even without making errors identifying the installation disk -, without disconnecting the nvme pcie macOS drive, overwrites something in its EFI partition?
 
Last edited:

Going Bald

Moderator
Joined
Aug 14, 2010
Messages
22,511
Motherboard
GA-X58A-UD7 Rev.1 BIOS F7
CPU
Intel Xeon W3670
Graphics
RX580
Mac
iMac, MacBook Pro, Mac mini
Classic Mac
iMac
Can there be the problem that the installation of Windows 10 (or Linux) - even without making errors identifying the installation disk -, without disconnecting the nvme pcie macOS drive, overwrites something in its EFI partition?
With Linux, no. Linux will install its EFI boot files to the EFI of the drive it is installed on.
With Win10, yes. Windows wants its boot files in the EFI of the first drive found when the system does its boot-up indexing. The Win10 installer has been known to put the EFI partition and boot files on drives other than the target drive. If you are unable to disable a port it is best not to install the second M.2 drive until you have Win10 installed, updated and running with all 3rd party software you have installed and ready to run. This can be a PITA if you have to remove side covers and GPUs to get to the slot, but it is one way to ensure Win10 has only one drive available for installation.
 
Joined
Nov 18, 2015
Messages
115
Motherboard
Gigabyte Z390 Designare
CPU
i9-9900K
Graphics
RX 580
Windows wants its boot files in the EFI of the first drive found when the system does its boot-up indexing. The Win10 installer has been known to put the EFI partition and boot files on drives other than the target drive.
Could this problem be avoided by setting the windows 10 boot drive as "first" in the BIOS option "Hard Drive / CD / DVD ROM Drive / Floppy Drive / Network Device BBS Priorities" (when available ) during installation?
If you are unable to disable a port it is best not to install the second M.2 drive until you have Win10 installed, updated and running with all 3rd party software you have installed and ready to run.
Does this mean that this problem can occur even during normal windows 10 updates or only during installation?
 
Last edited:
Joined
May 4, 2019
Messages
1
@lentife,

I have two Nvme drives on my main video edit (White Knight) Build ... 2 x Samsung Evo 960 NVMe SSD's High Sierra on one, Windows 10 on the other .... rather than use a EFI partition on one of the NVMe drives for Clover i bought a 8GB SATA SSD for just a few pounds ... similar to this one:-

https://www.ebay.co.uk/itm/SANDISK-SDSA5AK-008G-8GB-SATA-6-0-Gbps-SOLID-STATE-DRIVE-SSD/183192654959?hash=item2aa722146f:g:Iy0AAOSwNkxa3aCr

Its 8GB but 4GB or even 2GB will do just fine. I formatted it as GTP and installed Clover on to the EFI partition on that and configured the BIOS to boot form it.

The advantage is that if anything ever happens to your OSX or Clover configuration its easy to remove and and play with on anther machine ... in my case i usually connect it to my laptop using a USB to SATA adapter Y cable ....

You can use the rest of the 8GB drive as an installer and recovery drive or just a small data drive ...

This method has saved me several times in the past ... these days now that HS supports 3rd party NVMe drives its not so important but if you have spare/unused SATA controller i think booting the system from a small capacity dedicated boot SDD makes good sense.

Just thought i'd share my method
Cheers
Jay
Dude, you should make a complete tutorial of this in youtube or something. Please
 
Joined
Jun 10, 2019
Messages
1
Motherboard
Gigabyte B360m D3H
CPU
i5 8400
Graphics
RX 580
Mobile Phone
iOS
@lentife,

I have two Nvme drives on my main video edit (White Knight) Build ... 2 x Samsung Evo 960 NVMe SSD's High Sierra on one, Windows 10 on the other .... rather than use a EFI partition on one of the NVMe drives for Clover i bought a 8GB SATA SSD for just a few pounds ... similar to this one:-

https://www.ebay.co.uk/itm/SANDISK-SDSA5AK-008G-8GB-SATA-6-0-Gbps-SOLID-STATE-DRIVE-SSD/183192654959?hash=item2aa722146f:g:Iy0AAOSwNkxa3aCr

Its 8GB but 4GB or even 2GB will do just fine. I formatted it as GTP and installed Clover on to the EFI partition on that and configured the BIOS to boot form it.

The advantage is that if anything ever happens to your OSX or Clover configuration its easy to remove and and play with on anther machine ... in my case i usually connect it to my laptop using a USB to SATA adapter Y cable ....

You can use the rest of the 8GB drive as an installer and recovery drive or just a small data drive ...

This method has saved me several times in the past ... these days now that HS supports 3rd party NVMe drives its not so important but if you have spare/unused SATA controller i think booting the system from a small capacity dedicated boot SDD makes good sense.

Just thought i'd share my method
Cheers
Jay

Hi!
I am new here and also starting to build my OSX/Wind10 from scratch!
All hardwares are compatible since I check hear before buying.
I have a Seagate SSHD 1TB for OSX and a Samsung HD 500MB for Win10 (want the bigger for MacOSX).
After reading your post, I am thinking about buying a SSD Kingston M.2 A400 120 GB and boot OS from it.
I've read a lot, but I still have doubts:

1) Should I use the HD500MB for MacOSX or is it ok with de SSHD?
2) Should it boot both OS (MacOSX and Win10) from SSD M.2 120GB? Or only one, if this way, I would prefer MacOSX.

Tks for helping !
 

jaymonkey

Moderator
Joined
Aug 27, 2011
Messages
2,680
Motherboard
ASRock-Z97 EX6
CPU
i7-4790K OC @ 4.8GHz
Graphics
Vega 64LC + HD4600
Mac
MacBook Air, MacBook Pro
Mobile Phone
Android, iOS
I have a Seagate SSHD 1TB for OSX and a Samsung HD 500MB for Win10 (want the bigger for MacOSX).

1) Should I use the HD500MB for MacOSX or is it ok with de SSHD?
2) Should it boot both OS (MacOSX and Win10) from SSD M.2 120GB? Or only one, if this way, I would prefer MacOSX.

@RSRC-BR.

If you want to dual boot Windows and MacOS then it's much easier to install each OS on its own drive.
MacOS will run much better if installed on a SSD and use the HDD as a data drive.

Cheers
Jay
 
Last edited:
Joined
Sep 20, 2012
Messages
35
Motherboard
ASUS ROG MAXIMUS HERO X Z370
CPU
i9-9900
Graphics
RX 580
Mac
iMac
Mobile Phone
iOS
@SardusX,

Technically no ... as long as you can identify which drive is which within each operating systems installer then you can leave both connected. However even the best of us some times make mistakes .... i've seen a few cases where someone has two identical drives installed and they some how mistook one for the other during installation and inadvertently erased the wrong one while installing a OS ....

So if you want to play it 100% safe .. remove the Windows NVMe while installing MacOS and vice-versa, thats what i did.

Yes it can be a pain as some motherboards require you to remove the GPU to gain access to certain M.2 slots (as in the case of my AS-Rock Z98 Motherboard) but it's worth it for piece of mind in my opinion.

Cheers
Jay
Hi Jay,

Do you happen to know if there are options inside Windows 10, to prevent any access to the OS X drive ?
(Just to be extra safe I don’t destroy the OS X drive by accident)

Kind regards,

Chimiel
 

jaymonkey

Moderator
Joined
Aug 27, 2011
Messages
2,680
Motherboard
ASRock-Z97 EX6
CPU
i7-4790K OC @ 4.8GHz
Graphics
Vega 64LC + HD4600
Mac
MacBook Air, MacBook Pro
Mobile Phone
Android, iOS
Do you happen to know if there are options inside Windows 10, to prevent any access to the OS X drive ? (Just to be extra safe I don’t destroy the OS X drive by accident)

@Chimiel,

Windows can not read or write to HFS+ or APFS volumes without a 3rd party file system support driver being installed.

The only thing you need to be mindful of is that if your booting windows using UEFI than it can write to a EFI partition to update its boot loader .... but even then it will only write to the "microsoft" and "boot" folders so its always worth keeping a backup of your EFI boot partition just to be on the safe side.

Hope this answer your question ....

Cheers
Jay
 
Joined
Sep 20, 2012
Messages
35
Motherboard
ASUS ROG MAXIMUS HERO X Z370
CPU
i9-9900
Graphics
RX 580
Mac
iMac
Mobile Phone
iOS
@Chimiel,

Windows can not read or write to HFS+ or APFS volumes without a 3rd party file system support driver being installed.

The only thing you need to be mindful of is that if your booting windows using UEFI than it can write to a EFI partition to update its boot loader .... but even then it will only write to the "microsoft" and "boot" folders so its always worth keeping a backup of your EFI boot partition just to be on the safe side.

Hope this answer your question ....

Cheers
Jay
Thnx Jay,

That clears things up,

Kind regards
 
Top