dual boot W10 upgrade

User discussion and information resource forum for BootIt Bare Metal.

dual boot W10 upgrade

Postby hime3 » Sat Aug 13, 2016 1:06 pm

I intend to upgrade Win 8.1 to Win10 using ISO burned to DVD or upgrade on USB flash drive.
Use BMM and BootNow to dual boot between Win8.1 and Win7Pro.
BMM hide on auto.
Win 8.1 is active partition.
Converted GPT to MBR/EMBR.
Fast Startup disabled.
CSM legacy mode set in BIOS.
Have current v2.99 images of OS's each with BootIt EMBRM.
No image of 2T HD.
To upgrade Win8.1 only, and avoid any HD or partition corruption, is any precaution needed to assure Win10 will upgrade only Win8.1?
thanks
hime
hime3
 
Posts: 44
Joined: Sun Jan 01, 2012 10:47 am

Re: dual boot W10 upgrade

Postby mjnelson99 » Sat Aug 13, 2016 3:01 pm

Would it work if you start the upgrade from within Win 8?

On 8/13/2016 3:06 PM, hime3 wrote:
> I intend to upgrade Win 8.1 to Win10 using ISO burned to DVD or upgrade on USB flash drive.
> Use BMM and BootNow to dual boot between Win8.1 and Win7Pro.
> BMM hide on auto.
> Win 8.1 is active partition.
> Converted GPT to MBR/EMBR.
> Fast Startup disabled.
> CSM legacy mode set in BIOS.
> Have current v2.99 images of OS's each with BootIt EMBRM.
> No image of 2T HD.
> To upgrade Win8.1 only, and avoid any HD or partition corruption, is any precaution needed to assure Win10 will upgrade only Win8.1?
> thanks
> hime
>
>
mjnelson99
 
Posts: 768
Joined: Thu Aug 11, 2011 6:24 pm

Re: dual boot W10 upgrade

Postby TeraByte Support(PP) » Sat Aug 13, 2016 5:30 pm

If there are any other important partitions on the drive I would recommend backing them up too. Don't figure that the upgrade is going to leave everything else be. If it can it may create an additional partition, which is not usually desired, and if it can't see the hidden partitions then it may overwrite them.
Paul Purviance
TeraByte Support
TeraByte Support(PP)
 
Posts: 1108
Joined: Thu Aug 11, 2011 5:51 pm

Re: dual boot W10 upgrade

Postby CyberSimian » Sun Aug 14, 2016 3:20 am

hime3 wrote:
> Converted GPT to MBR/EMBR.
> To upgrade Win8.1 only, and avoid any HD or partition corruption, is any
> precaution needed to assure Win10 will upgrade only Win8.1?

If you want a multiboot system, the following should work and preserve your existing partitions; as always, BACKUP your system first, in case it all goes horribly wrong. Procedure:

(1) Unlimit primaries in your BIBM settings.

(2) Create an EMBR for each internal disk in your system.

(3) For the disk that is the target for the installation, create the partition to which you want to install Windows (e.g. 50 GiB), plus three tiny partitions at the end of the disk (e.g. 1 MiB each). Call these latter partitions FILLER1, FILLER2, and FILLER3. In your case, you want to update an existing Windows 8.1 partition, so that is the partition to use.

(4) Create a boot item that specifies WINDOWS, FILLER1, FILLER2, and FILLER3 as the partitions to include in the MBR for that disk. If your Windows 8.1 installation already uses one or more extra partitions, include those, and then fill up the remainder of the MBR with the FILLER partitions. Maintain whatever partition order already exists for Windows 8.1 and its extra partitions.

(5) For other internal disks in your system (if you have any), create four tiny 1 MiB partitions at the end of each disk. Call them FILLER1, ..., FILLER4. Place these in the MBR for that disk in the Windows boot item.

(6) Now start the installation of Windows, and when asked, select the 50 GiB partition as the target for the installation. In your case, Windows will likely pre-select the Windows 8.1 partition.

(7) At the end of installation, you can remove the FILLER partitions from the MBR in the boot item, and replace them with your data partitions. However, don't delete the FILLER partitions; leave them on your disks in case you need them again in the future.

The reason for this rigmarole is the following:

(a) If Windows sees any unused space on either the target disk or other internal disks, Windows will use it to create extra partitions, possibly overwriting your data in partitions that Windows cannot see.

(b) If Windows does not see any unused space, it will shrink the largest partition in order to create some unused space that it can use for the extra partitions.

(c) The only way to stop Windows doing this is to ensure that there are no unused entries in the MBR. Windows does not delete existing partitions. Hence, if there are no unused entries in the MBR, there is nowhere for Windows to place the extra partitions, so it won't create them. So no risk of overwriting the other partitions that Windows cannot see.

So you need three FILLER partitions on the target disk, and four FILLER partitions on each of the other internal disks. This procedure has worked for me in the past (Vista several years ago, Windows 7 last week), but there are many variations possible, so if I have omitted a vital step, please post a correction!

-- from CyberSimian in the UK

Edit: Changed size of Windows partition from "50 MiB" to "50 GiB". The FILLER partitions can indeed be 1 MiB in size.
Last edited by CyberSimian on Sun Aug 14, 2016 9:32 am, edited 2 times in total.
CyberSimian
 
Posts: 47
Joined: Wed Aug 10, 2016 5:13 am

Re: dual boot W10 upgrade

Postby TeraByte Support(PP) » Sun Aug 14, 2016 8:31 am

For drives that aren't necessary for the upgrade/update, you can also disconnect them or, if the BIOS allows, disable the ports. This way, they're not ever seen and no changes to them are needed.
Paul Purviance
TeraByte Support
TeraByte Support(PP)
 
Posts: 1108
Joined: Thu Aug 11, 2011 5:51 pm

Re: dual boot W10 upgrade

Postby CyberSimian » Sun Aug 14, 2016 11:55 am

TeraByte Support(PP) wrote:
> For drives that aren't necessary for the upgrade/update, you can also
> disconnect them or, if the BIOS allows, disable the ports. This way,
> they're not ever seen and no changes to them are needed.

I used the "disconnect other drives" trick for a tower system in the past. But most laptops are difficult to open in order to disconnect disks, and the BIOS in my Lenovo does not have any settings to disable the hard disks.

Of course, most laptops only have one hard disk anyway, so not a problem. But if you have both an SSD and a separate hard disk in your laptop, creating an EMBR for each disk and using the FILLER partitions may be the simplest solution.

-- from CyberSimian in the UK
CyberSimian
 
Posts: 47
Joined: Wed Aug 10, 2016 5:13 am


Return to BootIt Bare Metal