understanding bootrec fixmbr, fixboot, rebuildbcd.

Making progress with those links Greg, very grateful for your help.

I see (I think) the "MBR" is just the GPT Header at logical block 1.

The "BCD Store" is a table of boot menu options that I guess correspond to the "windows boot manager" option in the BIOS and eg allow windows to manage the boot process eg when I run setup from a USB stick, so it can change the boot to the hard drive when required. And resides in the system partition.

I've assigned W to partition 1 and V to partition 5. Neither show any files even when i check "show hidden files".

I cant find this (I'm on W11 Home 21H2) "File Explorer > View > Options > Change Folder and Search Options > View > enable Show Hidden Files and uncheck Hide Protected Operating System Files, approve security box, Apply, Save."

The Free space is showing no content in those partitions?

CDEdit /v shows this:

John -

System partition is to set the files apart from Windows on C that boot Windows so nothing can easily access them to corrupt them or clog their partition - since it doesn't have a drive letter nothing like a backup program can inadvertently write there.

What is the master boot record (MBR):

https://www.techtarget.com/whatis/definition/Ma...

What is the BCD Store:

http://www.mistyprojects.co.uk/documents/BCDEdi...

The list you show appears to be typical factory install which has the extra Recovery partition containing tools installed at factory. Please post a screenshot of Disk Management, which I read like a doctor reads X-rays. Follow the steps here so I can see everything needed to advise you: http://answers.microsoft.com/en-us/windows/foru...

The contents of Recovery partition is often hidden, you can try to unhide in File Explorer > View tab > show Hidden files (checkbox) and also in File Explorer > View > Options > Change Folder and Search Options > View > enable Show Hidden Files and uncheck Hide Protected Operating System Files, approve security box, Apply, Save.

The way to know if one of the Recovery partitions is working is to try to trigger Advanced Startup Options one of these ways: https://www.tenforums.com/tutorials/2294-advanc...

I would leave both Recovery partitions until the next Clean install and then properly clear all partitions off the drive before reinstalling Windows doing the gold standard Clean Install here: http://answers.microsoft.com/en-us/windows/wiki...

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Linked tutorial was written by a trusted Microsoft MVP

Thanks Greg, that explains a lot, "bootrec /fixmbr which is for the old Legacy MBR drives"

useful links I'll need to study, but I've not seen info on what the system partition is for,

nor what the boot record and bcd store do - I'm assuming they are located on the system partition?

My C drive (Win7 upgraded to 10, upgraded to 11) has this structure:

If I assign a letter to either of the recovery partitions they appear to be empty

Do I need to install a recovery environment to partition 5?

Hi John. I'm Greg, 10 years awarded Windows MVP, here to help you.

Those commands can still work, except for bootrec /fixmbr which is for the old Legacy MBR drives as you note. They are integrated into this guide which covers everything possible to get unbootable Windows started, including the sequencing for the powerful RebuildBCD command:

http://answers.microsoft.com/en-us/windows/wiki...

The drive map you posted is the correct layout for most standard UEFI Windows installs, the EFI System partition which boots Windows, followed by small hidden MSR partition for Bitlocker, C drive and Recovery partition which holds the WinRE repair tools that popup Automatic Repair when WIndows won't start, and which are explained more here: https://www.tenforums.com/tutorials/2294-advanc...

More here on the modern UEFI BIOS which has been the standard for ten years now:

http://www.howtogeek.com/175649/what-you-need-t...

https://www.marksei.com/bios-uefi-explained/

Feel free to ask back any questions. Based on the results you post back I may have other suggestions if necessary.

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