which Partitions should I delete when installing Windows 10

[xAIMx]

Hello!

I'm sure it's been answered before, but I have not been able to find any consistant answers, when it comes to my exact situation, and I wanna be safe rather than sorry!

I'm trying to install Windows 10 from a USB, and I get the error "Windows cannot be installed on this disk. The selected disk has an MBR partition table. On EFI systems, Windows can only......"

I understand that if I delete my Partitions, it will solve it, but I'm unsure if that means everything there is or just the small ones. I formatted both my HDD (1tb) and my ssd (256gb) and I wanna run Windows on the SSD, do I just delete every single one of these?

http://puu.sh/tcXNy/ab402c400b.jpg

Any help is appreciated, I've never worked with partitions, so I just wanna be sure

 

[MPF-Dean]

Hey xAIMx,

When doing a complete fresh install you can safely delete all partitions until they merge into one, click NEW to create the new partition and then install windows. Even on a retail laptop/PC with a recovery partition, as long as you have a windows OS disk and know how to download drivers (obviously need an internet connection), you can safely delete all partitions as long as you install the OS (otherwise it wont boot into anything just BIOS because there's no OS installed on the HDD). Note: Only delete a partition if you either have a back up or no need for the data on it, because once deleted it is pretty hard to recover.



- LE

 

[xAIMx]

Hey xAIMx,

When doing a complete fresh install you can safely delete all partitions until they merge into one, click NEW to create the new partition and then install windows. Even on a retail laptop/PC with a recovery partition, as long as you have a windows OS disk and know how to download drivers (obviously need an internet connection), you can safely delete all partitions as long as you install the OS (otherwise it wont boot into anything just BIOS because there's no OS installed on the HDD). Note: Only delete a partition if you either have a back up or no need for the data on it, because once deleted it is pretty hard to recover.



- LE

Alright! I deleted them all and was left with two, my HDD and SSD, and Windows will install just fine into both of them! Thank you!

 

[MPF-Dean]

No worries, sometimes windows will create a system partition so just make sure when you click install/next you have your primary HDD/SSD selected.

- LE

 

[Colif]

i would take the 1tb drive out of PC before installing win 10, even if you do want to wipe it. Reason being win 10 has nasty habit of putting the boot sector on the 2nd drive and if/when you take it out, PC won't boot off SSD

 

[Colif]

reason it left you with 2 drives is Windows isn't magic, it can't combine 2 physical drives into one blob of unallocated space. Win 10 will create 4 partitions on the ssd once its ready

Refer step 13 here: https://www.tenforums.com/tutorials/1950-windows-10-clean-install.html

 

[xAIMx]

i would take the 1tb drive out of PC before installing win 10, even if you do want to wipe it. Reason being win 10 has nasty habit of putting the boot sector on the 2nd drive and if/when you take it out, PC won't boot off SSD

Alright, I'll do that, since I don't know if I'll be keeping that HDD or upgrading soonish

 

[MPF-Dean]

Hey Colif,

Can you explain that please? I use an SSD in my PC as the primary boot drive and have a HDD in there as well for storage. I take the HDD out sometimes to transfer things to my other PCs and my computer still boots fine. I have built many PCs, with the same set up. SSD primary HDD secondary, removed the secondary and the PC can still boot fine?

I have just not heard of that sorry.



- LE

 

[Colif]

It doesn't always do it, I think it depends on if 2nd drive has any blank unallocated space on it or not. I know it didn't do it when I fresh installed win 10 last year but my 2tb drive didn't have any free space on it.

I think its a feature of GPT. I know it happens as lots of other people around here suggest same thing

 

[13thmonkey]

LE it's whether the HDD is fitted and powered at the time of installation. I'm sure that there is some logic as to where the 100MB system partition goes, perhaps it is on sata0, but it is very common to find questions along the lines of 'I removed this HDD and now windows on my SSD won't boot'

So it is best to only have the proposed system drive in place at installation time, so that windows doesn't try and be helpful.

 

[MPF-Dean]

I see, so 2 blank drives and windows gets confused but if one has some data on it, it will put the boot sector on the blank/select drive?

- LE

 

[13thmonkey]

I see, so 2 blank drives and windows gets confused but if one has some data on it, it will put the boot sector on the blank/select drive?

- LE

It might put it on the full drive, I'm sure that in the early days there were occasions where it just reformatted the drive it wanted to use, for the time taken to pull the power or data cable it's not worth the risk.

 

[MPF-Dean]

No worries guys, always better to be safe than sorry down the track if needing to pull out the HDD. I haven't came across it yet but there's always that one time that's the worst time haha. I will keep what you have said in mind and future builds will start with one boot drive until finished OS installation. 😀

- LE

 

[Colif]

Not sure the UEFI boot even cares what sata cable the boot drive in on, it uses the GUID of the drive to locate it, it should be using Windows Boot Manager in the bios to tell the PC what drive to boot off.

GPT tries to sprinkle copies off its boot files around on the install to make recovery easier if the boot file gets corrupted

 

[Colif]

if the 2nd drive already has an EFI partition, it would use that over making a new one.

 

[13thmonkey]

which is odd as it makes the system susceptible to either drive failing, and not just the windows drive.

 

[Colif]

imagine how confusing it would be if every boot drive had an EFI partition, how would it know which to boot off? How would it see previous or other OS?

No, having 1 makes sense as it lets it boot them all from 1 place. People like fast boot times, 15 seconds is too slow now.

Lots more info on UEFI boot: https://www.happyassassin.net/2014/01/25/uefi-boot-how-does-that-actually-work-then/

 

[13thmonkey]

I suppose if there was a process whereby it had a 'master' set of information and copied it in idle time, that might be useful, would have to account for HDD's moving between machines though.

 

[Colif]

The windows boot manager in the UEFI has a list of drives in it, its how it can boot different Operating systems. It includes the drive ID and the partition number on the drive to look in. So if the top drive in list isn't there, it goes to next. It has to have a list here since GPT doesn't boot like MBR, the EFI partition can be anywhere on disk, not necessarily at the start. Its backwards compatible and can boot mbr if need be, it just emulates legacy boot. How else would it boot win 7?

this boot loader can be edited from inside operating systems so its easy to get the right boot order without needing to enter UEFI and play with the order of drives like BIOS. You just have Windows Boot Manager at top and ignore rest of list.

That would mean you could have hot swapable and other devices in wbm and they can be removed/replaced at any time without having to edit the boot order everytime.

I just read that link but a lot of it relates to linux and I stopped knowing what they were talking about after a while.