Interesting Snag in Completely Clean Reinstall (MBR vs GPT)

[britechguy]

Well, the Lenovo ThinkPad X260 I had written about the other day has turned in to one of those, "I've never seen anything like this!!," experiences from several angles.

First was the failure mode of Windows 10 previously documented in my earlier topic.

The second of which was finding out that whoever originally set this machine up had the Windows OS drive partitioned MBR. The machine was purchased, new, in Thailand, and is not all that old. Whoever set it up partitioned the drive such that the user data was being stored on one logical drive/partition and Windows 10 was in its own. That turned out to be very handy as far as preserving the user data this time around, though I copied it off before starting anyway, as I had anticipated undoing this arrangement.

Well, if you create Windows 10 installation media using Rufus, and make the reasonable presumption that any newer machine that started out life with Win 10 will be partitioned GPT, but it's been partitioned MBR, you run into the situation where your install media is, for all practical intents and purposes, trash.

After re-creating the Win10 install media for MBR, the install went OK, but:

1. I was never presented with any option to reinitialize the whole HDD and start from scratch.

2. I could not SHIFT+F10 out to command prompt/Power Shell to run diskpart no matter what I did.

Windows 10 did reinstall on the logical drive/partition it had been on before, and successfully. This was, however, a completely clean reinstall experience unlike any other I've had over the last 5 years.

Now, when you have a machine that won't boot into Windows 10 as I did when this all started, is there some easy way to determine how the OS drive is partitioned? I would still expect GPT as the default, but it would be really handy to have a method to determine this definitively.

 

[Sky-Knight]

Microsoft recently caused that break in Rufus by the way... they also busted the secure boot bits so you have to turn that off again.

But it is none-the-less a fact that you have to choose, via desperate installation media if you want EFI or BIOS boot.

Both installs default to a partitioner... so I'm not sure how you managed to miss that, or why it wouldn't have been present.

As for figuring out if the install is EFI or BIOS, you have to look at the partitions on the disk.

Open a command prompt during the PE portion of the install, run disk part, and run: list disk

The output has a GPT column, if there's a * there, it's GPT, and therefore EFI.

 

[britechguy]

If I could open command prompt . . .

Therein lies the problem. I am explaining a situation that I had not ever encountered, and do not hope to encounter again.

I know how to do this stuff when things are operating as expected, I was just hoping someone might have had this bizarre exception condition, but sometimes that's not to be.

I did get to the partitioner, but you cannot install Win10 using Rufus created media that was set up for GPT if the actual drive is MBR. I got a message at that stage, in tiny print, that I couldn't install because the drive was MBR. Had I known that from the get go, which I would not have expected, I'd have created MBR install media to begin with.

I always download the ISO, and got a fresh copy today, as I find I have reason to use the ISO later, most often for repair installs. I then use Rufus to create the bootable install media, and it's worked without issue for years now (not that I haven't heard about the occasional burps).

 

[sapphirescales]

You don't wipe the drive before reinstalling Windows? I always either extract the drive and use the LLF (Low Level Format) tool to destroy all partitions on the drive or if I don't feel like extracting the drive I run the tool in a portable version of Windows 10. I don't let the LLF tool complete. I just use it to start from scratch.

In any case, it's pretty rare that I reinstall Windows on the same drive. 99% of the time it's either swapping out a hard drive with an SSD or swapping out a small SSD with a larger one.

EDIT: And on top of that I use images. I very rarely install Windows from scratch. It just takes too damned long! I can image a computer in 5 minutes. It takes at least 20 minutes to install and configure Windows 10 from scratch (it could take HOURS if the stupid start menu apps don't install right away).

 

[Sky-Knight]

If you want to swap between MBR and GPT you do have to wipe the drive, the bit that's missing here... is the fact that you can get to the command prompt BEFORE the install actually runs. From there you can diskpart, then clean

POOF no more partitions, reboot, install.

 

[britechguy]

There is really no point in discussing this further.

I could not, for whatever reason, break out to command prompt no matter what tricks I tried, and I've been able to do so in all cases other than this one.

I know what to do when things are working as they should. There's no trick to that.

 

[NJW]

Whoever set it up partitioned the drive such that the user data was being stored on one logical drive/partition and Windows 10 was in its own.

I'll wager that was the cause of the boot problems that you mentioned in the other thread. IMO, alternative locations for system folders (including standard user folders) will eventually call in sick.

Did you not get any hint to disk partitioning from the drive imaging step, before you started work ... ?

 

[Sky-Knight]

@britechguy, boot to setup media, see blue window WIndows setup window, shift + f10?

I've had two 1909 installs require that... the troubleshooting mode stuff didn't have the right buttons anymore. But others did... so you're not nuts, but I also don't know why. My best guess is there's a recovery partition on the disk with an answer file in it.

But seriously, log that shortcut into your head, practically anywhere in Windows 10 setup it works to fire up a command prompt.

 

[britechguy]

@Sky-Knight,

I suggest you read material I've posted, on this forum and elsewhere, again:

Doing a Completely Clean (Re)install of Windows 10 Using Media Creation Tool to Fetch the Win10 ISO File

Doing a Completely Clean (Re)install of Windows 10 Using Media Creation Tool to Create Bootable Win10 Install Media on a USB Thumb Drive

as well as point #2 in my initial post. It is beyond galling to have what one has clearly stated ignored, then to be talked down to as though one has no idea that such a technique exists. It does exist and it would not work. Period, end of sentence. I have no reason to misrepresent the experience, as it sure doesn't serve me nor do I care to mislead, ever.

There's nothing for me to log, as I am very, very well aware of what you're asking me to remember. But I am heartened that you've stated that I have not taken leave of my senses and that there have apparently been other rare instances of this sort of thing.

@NJW: Since I knew that Windows was entirely lost, and I was easily able to copy off the user data from the partition/logical drive it was on, I did not even bother to take a drive image, as there was nothing restorable. When I figured out it was MBR was when you got to the step in Windows installation where you picked where you wanted it to go, and was promptly told that the partition was MBR and that I could not use the media I had, which required GPT, and I could not break out at that time to do my usual steps with diskpart, which had been my intention.

 

[Sky-Knight]

But the screen where you pick the destination partition IS the partitioner...

 

[britechguy]

But the screen where you pick the destination partition IS the partitioner...

Yes, and?

I couldn't break out there, nor would it let me reinitialize it GPT. I understood what I was seeing, what I'm telling you is that it was not allowing a number of things it typically would. I can't explain it. It was what it was.

Whether anyone chooses to believe me or not at this point is irrelevant, as I eventually triumphed over the situational obstinance of a tool I've used many, many times. I could not get the partitioner to allow me to use it nor could I break out (and I tried at every step the second time I decided to power off and start from the very beginning) to get to command prompt. Under normal circumstances I would have broken out and used diskpart to wipe the entire drive via the clean option and then done a convert gpt afterward.

Now this can serve more as a warning that, "This could happen to you, too." And, heaven knows, I don't wish it on anyone else.

 

[NJW]

Since I knew that Windows was entirely lost, and I was easily able to copy off the user data from the partition/logical drive it was on, I did not even bother to take a drive image, as there was nothing restorable.

Only with hindsight. Reading your initial story again, in the early stages you were trying to recover from a possible user profile corruption and diving into System Restore. You didn't know that the user data was on a separate partition (which, in itself, doesn't make it bullet-proof, of course). It's a brave tech. that goes that route without a system image.

 

[britechguy]

You didn't know that the user data was on a separate partition (which, in itself, doesn't make it bullet-proof, of course).

In my experience, System Restore (when it works) just works or it doesn't. Have never lost data from trying it. In this case I got the all too usual, "didn't work - files/folders unchanged."

By the time I was doing the Windows reinstall I knew the user data was stored on its own partition and that data had been copied off to a backup drive as well. I had fired up the machine using live Linux Mint to find out what was going on with the drive and what I could get off of it prior to doing the Windows reinstall.

There was absolutely no point in a system image under the prevailing conditions, as what could be "restored from" had already been backed up. Windows 10 was already entirely blown. A system image is only useful if you can restore a functional system from it.