Warning - UEFI install and secondary hard drive with Extended/Logical partitions.

Saltgrass

Excellent Member
Microsoft Community Contributor
#1
It has come to light, that a UEFI installed system, will fail to boot if a secondary drive is attached which contains logical partitions. This would have to be an MBR configured drive, of course, but if it has at least one primary and one extended partition, it will stop Windows 7 and Windows 8 from booting.

This can be a significant problem for several reasons. First, most folks that have UEFI installs do not even know. Secondly, information about extended or logical partitions on a secondary drive will not normally be given by a poster.

I can see this occurring in situations where someone gets a new system and attaches their old drive to recover data...

And I should add, if the drive is connected during a Windows 7 install, the install will fail during the first reboot.
 


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Trouble

Noob Whisperer
#2
Thanks for the info Clark.
Will try to keep it in mind and point to this thread for relative information.
Can we assume that this occurs only when the second drive is attached using internal IDE or SATA connections and not when connected using USB or eSATA?
Since I don't have a board that supports or includes UEFI yet, I haven't ran into this issue. Is there any work around for this issue with respect to a BIOS setting?
 


Saltgrass

Excellent Member
Microsoft Community Contributor
#3
I have not yet tested on an external drive. But I will shortly if I can arrange it, since my current external drive is GPT configured.

If I read a comment correctly, any systems marked as Windows 8 compatible will have to be UEFI capable. Systems may not be installed that way, but I would expect to see more systems showing up.
 


Trouble

Noob Whisperer
#4
Thanks Clark. Keep us posted.
I was just wondering if this problem is a product of the "Secure Boot" feature which I believe is present in most if not all Current UEFI schemes, and if by either manipulating those settings to the extent that the firmware will allow or else by disabling the secure boot feature if you could in fact regain control and use of your post install, added, storage devices.
Protecting the pre-OS environment with UEFI - Building Windows 8 - Site Home - MSDN Blogs
 


Saltgrass

Excellent Member
Microsoft Community Contributor
#5
I have now tested an external USB drive and the problem also exhibits using that. Another note, Ubuntu, when using an UEFI install, does continue to boot without error.

But I will have to say the Secure Boot option is not involved.

The reason I say that is my bios has a Secure Boot setting. You can use Legacy/UEFI or Windows 8 UEFI. The secure options do not become available until the Windows 8 UEFI option is selected. You then have a Standard or Custom option, and the Custom opens up all sorts of things. The best explanation I have seen is the Extended partition is confused with an EFI partition.

But Windows 7 will not boot at all with the Windows 8 UEFI selected. And Windows 8 still refused to boot, after selecting that option, when using the previously described configuration.
 


Pauli

Extraordinary Member
Premium Supporter
#6
Yeah well Bingo - that's probably why I lost all data on a HDD. I built a new computer, I had my old system HDD connected, unformatted, but was installing Windows 7 on a new SSD. It wouldn't install, I tried 4 or 5 times. So I started messing with partitions --- I'm not a master here :redface: --- I just meant to check them... but somehow, in the end, I lost 200Gb, some of it containing three years of work.

Thanks. I mean for the info - nothing sarcastic!
 


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