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E-66

Install Win 7 on MBR SSD... can I add a data-only GPT HDD?

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I'm confused about this based on something I read in the Windows and GPT FAQ on MSDN.

I'm building a new PC and already have everything except the SSD that I'll be installing the OS on (Win 7 x64).  Since I'll be getting a smaller SSD (probably 256 GB or smaller), I assumed I'd set it up with a MBR scheme.  My data-only HDD will be 3 TB, and I thought I had to set it up with a GPT scheme because of its size.  My confusion lies in what I read here, regarding using both MBR & GPT disks on the same system: https://msdn.microsoft.com/en-us/library/windows/hardware/dn640535(v=vs.85).aspx#gpt_faq_mixed_gpt_mbr

"Systems that support UEFI (mine does) require that boot partition must reside on a GPT disk. Other hard disks can be either MBR or GPT."

Is this accurate, or am I interpreting it incorrectly?  My 3 TB drive is going to be data-only.  I have ZERO experience with GPT.  My plan was to install Win 7 from USB to the SSD, and after it's set up to my liking I'd add in the 3 TB drive.  What will happen if I do this?  Based on the info from the link above, I'm interpreting it to mean that the system will look to the 3 TB drive for a boot partition, not find one, and then potentially not boot.

Some clarification about this would be appreciated.  Thanks.

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Posted (edited)

It is one of the classical yes/no answers.

The good :dubbio: guys that put together the EFI/UEFI "standard" (and then summed it up in some 2,200 - that is twothousandtwohundred - pages of specifications :w00t::ph34r:) had something (actually pretty vague and fundamentally "wrong" when it comes to backwards compatibility) in any case each and every UEFI vendor may have read in those pages everything and the contrary of everything so *anything* may happen.

In theory UEFI would provide an EFI "shell" which could be as powerful as a real mode OS, like - say - DOS, allowing to do almost anything in the phase before the OS is booted, in practice not only this shell has become a mere replica (with senseless graphical effects) of the settings you find in *any* BIOS, but noone (with a few exceptions that I can count on the fingers of one hand) develops any software for the EFI environment.

But (with some few exceptions of "pure UEFI" systems) most firmware implementations have - inside or besides UEFI - a CSM (Compatibility Support Module) which is simply a BIOS, just like the good ol'one.

So you shouldn't have any problem in booting in BIOS mode, and even in UEFI mode, there are anyway ways.

Some UEFI are (poorly IMHO) coded in such a way that they automatically disable CSM if they detect a EFI loader, that is an issue (that can be also fixed with a workaround or two, still it is more complicated).

The main "mistake" that people makes (BTW induced by the - I have to presume intentionallt UNclear communication from Intel, MS and friends) is that GPT "style" of partitioning (while part of the UEFI "standard") is totally independent from it.

An OS may (quite a few are) not able to boot in UEFI mode but perfectly capable to access a GPT disk (and most with a few tricks can be made into also booting from a GPT disk, even if the OS is said to be not able to).

Anyway the main thing that one must understand is that BIOS (or UEFI) are largely irrelevant once an OS like NT based systems are booted.

Typical boot sequences:

BIOS:

BIOS->MBR of first disk->PBR of activepartition on first disk->OS loader->rescan of system, HAL, drivers->booted OS

UEFI:

UEFI->OS loader listed in NVRAM, but residing on some device->rescan of system, HAL, drivers->booted OS

or:

UEFI->OS loader in FAT EFI partition on disk->rescan of system, HAL, drivers->booted OS

So, once booted, the system will be essentially (like 99.99999%) the same, of course ALL OS that can be booted in UEFI mode surely support GPT "style" disks, while systems that only can boot in BIOS mode usually do not support GPT disks for booting (but as said there are workarounds) but most support GPT for "data only" disks.

So, if you have a CSM in your UEFI you can ignore the UEFI and continue booting through  BIOS (and from MBR), if you have not a CSM module you can most probably (but it may need a tweak or two) boot from MBR, or you can have your boot disk as GPT (besides being in some regards a "stupid" standard it has some advantages over MBR, namely a replicated partition table that may come of use in case of disk corruption for recovery).

If you are going to multiboot different systems the BIOS (CSM) is still the best choice IMHO, one of the (senseless and evidently imposed to "push" something on users) is that with UEFI the OS must have the same bitness of the hardware, i.e. you cannot use a 32 bit Os on 64 bit hardware.

If you are going to use only one OS or a couple of new ones that support UEFI and GPT you may also use GPT only devices without issues.

jaclaz

 

 

Edited by jaclaz
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12 hours ago, E-66 said:

I'm confused about this based on something I read in the Windows and GPT FAQ on MSDN.

"Systems that support UEFI (mine does) require that boot partition must reside on a GPT disk. Other hard disks can be either MBR or GPT."

Yes it is incorrect, but it is the fault of the wording. It should be that if you set your boot type to UEFI, then the disk your OS resides on must* be GPT.

But, if you have no UEFI, or set your boot type to Legacy/CSM/BIOS, your OS disk can be MBR. Then if you put in another disk, it can be MBR or GPT.

The key is booting an OS. You can't normally boot an MBR disk with UEFI boot enabled, nor boot a GPT disk with Legacy enabled.*

Also in "normal" situations. There do exist systems or even firmware versions of consumer boards where these rules do not apply, but 99.9% of the time you won't run into a system like this.

*officially supported situations. :whistle:
Some smart people have figured out ways around it, as PoC, but I wouldn't use it outside of testing unless specifically required.

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42 minutes ago, Tripredacus said:

Yes it is incorrect, but it is the fault of the wording.

Brought to you by the same guys that call "system" what everyone else calls "boot" and call "boot" what everyone calls "system", BTW ;).

http://www.multibooters.co.uk/system.html

jaclaz


 

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Thanks for the replies so far.  As a reminder, I don't work in the PC industry in any way; I'm just a detail-oriented and techno-minded home user.  To me, UEFI means "fancy BIOS screens with a fancy background.... and you can use your mouse."  At this point my knowledge doesn't go beyond that.  I hit F2/delete during POST and I'm in it and looking around.

For this build I decided to go AMD Ryzen.  My mobo is an AsRock AB350M Pro4: http://asrock.com/mb/AMD/AB350M Pro4/index.asp   I'm looking at a PDF of the manual as I type this.  Under BIOS Features, it says it has an "AMI UEFI Legal BIOS with GUI support."  It has a lot of options, some of which I have no idea what they are.  There is a CSM entry, and it's enabled.  It says not to disable it unless a WHCK test is being run.  Underneath the CSM entry are the following: Launch PXE OpROM Policy, Launch Storage OpROM Policy, & Launch Video OpROM Policy.  Al are set to "legacy."  Is this enough info to tell you 'how' I'm booting?

As I mentioned in my initial post, I don't have my SSD yet, so in order to play around with my new hardware I hooked up an older SATA HDD that has a small FAT primary partition and several OS-sized logical partitions on it (jaclaz, I've read about and used your partitioning/boot strategies), and installed Win 7 from USB on one of them.  The info in the link above to the mobo says is designed for Win 10 only, but I had no trouble getting 7 installed.  This HDD was obviously originally set up in a MBR scheme.

I had assumed that I was booting with UEFI just because of how the background screen looked and because I had my mouse available.  Then I came across this on How-To-Geek about using UEFI instead of the BIOS, and confused myself a bit more: https://www.howtogeek.com/175649/what-you-need-to-know-about-using-uefi-instead-of-the-bios/

It talks about accessing the UEFI options from within Windows 8 & 10.  I know I'm running 7, and it mentions a legacy BIOS mode for older OSes, but I'm not seeing any options for that when I was poking around.  Probably because the mobo was designed for 10 only?

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2 hours ago, E-66 said:

Underneath the CSM entry are the following: Launch PXE OpROM Policy, Launch Storage OpROM Policy, & Launch Video OpROM Policy.  Al are set to "legacy."  Is this enough info to tell you 'how' I'm booting?

Unfortunately, no. You can't trust the board enough. I recommend that when you install your OS, you use your board's boot menu to manually select your bootable device. Even with Legacy set on all, UEFI is not disabled, and you may end up seeing UEFI boot options in the the boot menu anyways. For important steps like installing an OS, I always use the boot menu because I want to be completely sure it is doing exactly what I want it to do. Even on some recent boards, the boot menu will give UEFI boot options for DOS volumes...

I also recommend that your 3TB not be connected to the computer at all (power is ok) until after Windows is installed. Windows Setup can sometimes decide to write the boot files onto other disks, or even install Windows on teh wrong disk if you are not careful. Again, it is easier to just unplug the extra drives during this process so you can know exactly what is going on.

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@E-66

The motherboard provides UEFI only at inital boot, hence the USB mouse is working. 
If you enter the firmware settings, the mobo works at UEFI mode.
The motherboard speaks to the hardware at UEFI mode only.

On top of UEFI, the motherboard provides CSM emulation mode. This goes to the operating system.
The operatin system may detect a BIOS hardware, but it's a emulated one.
The hardware itself works at UEFI mode still, the firmware emulates this.
CSM mode is enabled at certain conditions.

The hardware manufactuer offers Windows 7 drivers, Windows 7 is supported.
http://asrock.com/mb/AMD/AB350M Pro4/index.asp#osW764Most likely the motherboard choose UEFI/CSM automatic currently.
If you boot a old MBR USB disk (no Windows 7 UEFI files added) , the motherboard switch to CSM mode.
I understand so far: there are no UEFI boot filles at the USB disk currently.
Windows 7 setup is launched a BIOS mode and installaion to a old MBR disk does work.

If you boot the same USB disk, the motherboard switch to CSM mode in future too. 
Windows 7 setup is launched a BIOS mode and installaion to a new empty SSD disk does work.
Windows 7 setup creates a MBR disk.

If you add a UEFI boot environment to this USB disk, the firmware may provide UEFI mode at USB boot.

Windows 8 & 10 can't access the UEFI options from within Windows, contrary you may configure next boot.
At reboot the machine boots to firmware settings automatically.

What do you wan't to get: Windows 7 at BIOS or UEFI mode at the SSD?
As for Windows 7 allone: use UEFI, if you use a 3 TB SSD. Well, not very likely. Keep BIOS mode: SSD at MBR and HDD at GPT.
What about the year 2020, Windows 7 end of life support? Do you like to upgrade then or keep Windows 7?
As for a multi boot environment, validate other operating systems too. Choose BIOS or UEFI mode.

To get UEFI boot choose, you may have to update your USB disk.


 

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@Tripredacus

Yes, I *did* use the new PC's boot menu option to select my USB flash drive in order to install Win 7 off of it (on the older HDD I mentioned above).... and it was the only HDD connected at the time.  I'll do the same in the future with the SSD before adding the 3TB drive.  I mentioned that in my initial post.

That being said, after I had 7 installed and working (this was a few weeks ago), I went back to the boot menu at start up because I thought I saw something I wasn't sure of, but ignored it at that time because I wasn't selecting it at that point.  It was the UEFI Shell option.  I've since gone back and selected it, and it brings up a command line interface.  I had no clue what to do even to poke just around in it, so I typed 'help' and saw a flurry of stuff go by and was only able to see the last third or half of it after the screen stopped scrolling.  The "/p" switch didn't work like in DOS, and I didn't know what to type to get it to stop after a page of info, so I just exited out of it.

@cdob

I worded my last post poorly.  I'm aware that there are Win 7 drivers on AsRock's site.  I used several of them during my install.

Regarding adding a UEFI boot environment to my USB disk, I did that as a test using the Rufus USB installer.  When I booted from the USB flash drive, I got to the screen where I could pick which partition to install to, and for each one I got a message that the partition or disk were not of the right type.  I expected that.  The HDD was MBR, and it was looking for GPT.

I plan on using Win 7 for as long as possible.  It may be the last version of Windows I use.  I also downloaded a 10 ISO and installed it and played around with it for a week.  Just didn't like it.  No experience with 8.  I plan on eventually dual booting this new PC with some variety of Linux.

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Another Q: If I set up the 3TB HDD in a GPT scheme, is the creating & formatting of partitions through Disk Management still the same?  If it is, then since this is going to be a data-only HDD, say I don't create any primary partitions on it, thus there are no partitions to be marked as active, and I make the whole thing 1 or more Logicals inside an Extended.....and I don't connect this HDD to the system until after I've installed Win 7 on the SSD.  Would this minimize the chance of any booting issues?

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5 hours ago, E-66 said:

Another Q: If I set up the 3TB HDD in a GPT scheme, is the creating & formatting of partitions through Disk Management still the same?  If it is, then since this is going to be a data-only HDD, say I don't create any primary partitions on it, thus there are no partitions to be marked as active, and I make the whole thing 1 or more Logicals inside an Extended.....and I don't connect this HDD to the system until after I've installed Win 7 on the SSD.  Would this minimize the chance of any booting issues?

Well you cannot make proper questions while making assumptions.

Your question is VOID :w00t: for not one, but TWO reasons :ph34r::

1) there is NO such thing as an "active" partition on GPT

2) ALL partitions on GPT are "primary" ones [1]

jaclaz

[1] this is not actually 100% correct, as there is a "special" kind of  partition (with an embedded MBR) that may in theory behave in a very similar way to an Extended partition, but in practice noone uses that particular GUI/format and I know of no OS that supports it.  
 

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Thanks for the lesson. :o

Followup Q: With what you said above in mind, when you access a GPT HDD in Disk Management in order to create 1 or more partitions, are the Extended/Logical options either grayed out or not made available at all?  Is the only option to create "a partition" because in GPT a partition is a partition is a partition?

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I believe that all you get is "New Simple Volume".

jaclaz
 

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