How do I re-create the 100mb partition?

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  1.    #21

    There seems to be no point in reinstalling just Win7 since you now have it configured correctly. Are there performance issues with the OS that need remedy?

    If you want to reinstall, this tutorial explains the best way to dual boot Win7 with Ubuntu: Dual-Boot Windows 7 and Ubuntu in Perfect Harmony

    Remember to wipe the HD before starting the reinstalls.
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  2. mjf
    Posts : 5,969
    Windows 7x64 Home Premium SP1
       #22

    M R said:
    I removed it and everything continued to work just fine. If I can I'll do it next time too (after wiping both partitions, I'm still at that step). My guess is that you are right and it won't boot because Windows' bootloader looks for the necessary files to boot in that partition by referring to it by its drive letter. However, since I'm using GRUB to boot Windows, and Linux does not need drive letters at all as it refers to partitions by device name (HD number 0, partition number 1, HD number 0 partiotion number 2, etc.), so I guess it just goes to the partiotion, fetchs the files and runs the boot process. That must be the reason why nothing bad happens when I change it. If I restore the MBR using Windows it will be a different story though.
    If System,active is part of the boot,OS partition (ie. no sys res 100MB partition), you obviously wouldn't remove the drive letter. But the the 100MB active, system reserved partition shouldn't normally have a drive letter assigned to it. It's for the OS and not the user to access. (of course except BCD changes).
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  3.    #23

    Bare Foot Kid said:
    The "System" partition drive letter cannot be removed, Windows will not start if that's done.
    Ted, can you test this? Obviously one can't remove drive letter from Win7 when it's system, but it seems like we've removed the letter from SysReserved before to keep backups from writing to it.

    If it doesn't need a letter and shouldn't have one, maybe it can be removed? Just askin...since I know you're just the guy to test these things. Don't mean to upset you.
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  4. Posts : 22,814
    W 7 64-bit Ultimate
       #24

    gregrocker said:
    Bare Foot Kid said:
    The "System" partition drive letter cannot be removed, Windows will not start if that's done.
    Ted, can you test this? Obviously one can't remove drive letter from Win7 when it's system, but it seems like we've removed the letter from SysReserved before to keep backups from writing to it.

    If it doesn't need a letter and shouldn't have one, maybe it can be removed? Just askin...since I know you're just the guy to test these things. Don't mean to upset you.

    Hello Greg.

    I would be glad to test it but I am currently in the middle of a simulation for another tutorial and I can't stop because the current info would be lost, I may/should have time tomorrow some-time and will report back to this same thread if I do.
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  5.    #25

    If OP is correct that GRUB was watiting for the 100mb System Reserved partition to return to start working again, then it might be referencing it by letter. I simply don't know enough about GRUB or Linux (another OS) to know for sure.

    Hopefully someone else will, or OP can try it once BFK reports if 100mb drive letter can be removed and returned successfully. I'd make a Macrium Reflect or free Paragon 10 image first so you can start over if necessary with the flexibility to reimage to specific partitions.
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  6. M R
    Posts : 31
    Windows 7 Ultimate 32 bit
    Thread Starter
       #26

    I did what BFK told me. I'm currently installing Windows again (because it had a lot of folder from the previous installation I didn't want to preserve. They are so many that I prefer installing everything again. Besides this way I can practice what you just taught me). Well, I have been able to boot Windows even after deleting the 100MB partition as long as GRUB is active. I also removed the letter and the 100MB partition disappeared from the sight of Windows, but not Linux, Linux still could acess, write to it, and boot Windows from it.

    Update: I did what BFK told me (wipe the 100MB partition and C:, then installed Windows) and the partition was automatically configured and the appropriate boot files are there. GRUB was (as usual) destroyed by Windows, rendering Linux inaccesible.

    I restored Linux and checked the reserved partition (remember that Windows does not see it, but Linux does). It turns out that the files in there are for the boot manager.

    Another thing: I did restore GRUB but did not modify it. It is still looking for the Bootloader in the 100MB partition. In other words, it is not aware of the wiping, formatting and installations that took place on the Windows side. Still, it can boot Windows 7 without any problem. This leads me to think that, for GRUB, drive letter does not matter (remember that GRUB is accessing the partition formerly know as E: but it doesn't raise any errors, meaning that letter does not matter for Linux, as I suspected before. it just looks for the boot files in there. As long as the partition exists, it will work).

    Final update: Everything went fine!! Windows is installed, the boot partition is invisible, the F8 menu worked (not anymore because Windows Bootloader is disabled and replaced by Grub, but who cares, I can use the CD), Linux is in its place and all I have to do is reinstall the software.

    Thank you guys this is wonderful. This is easily the best Windows support forum I know, you were quick and supportive (and didn't flame me because I'm more of a Linux user).

    Thak you all :)
    Last edited by M R; 04 Dec 2010 at 19:13.
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  7. M R
    Posts : 31
    Windows 7 Ultimate 32 bit
    Thread Starter
       #27

    gregrocker said:
    If OP is correct that GRUB was watiting for the 100mb System Reserved partition to return to start working again, then it might be referencing it by letter. I simply don't know enough about GRUB or Linux (another OS) to know for sure.

    Hopefully someone else will, or OP can try it once BFK reports if 100mb drive letter can be removed and returned successfully. I'd make a Macrium Reflect or free Paragon 10 image first so you can start over if necessary with the flexibility to reimage to specific partitions.

    No, no. Perhaps I wasn't too clear:

    GRUB, and Linux for that matter, don't care about letters. In Linux a partition is referenced by its device.

    We have a hard drive and two partitions.

    Windows would call them, C: and D: Now, there is a third partition: the extended partition containing D: but Windows won't confuse you with that (not in MyPC at least).

    Linux would say sda (SATA drive a) for the disk. And sda1 for C: (first partition in sda), and sda2 for the extended partition containing D:, and sda3 for D: itself.


    Long explanation:

    Now, you have to tell GRUB where the boot files are for it to be able to boot Windows. In the past you just told it where C: was, because there was no separate 100MB partition for booting up in previous windows versions.

    For Win7 though, you tell it to boot from sda1 (the 100MB partition). Now, if you format sd1, GRUB won't boot Win7 (because there is nothing it can run from there). But if you change the letter or hide the partition or whatever it will still boot from there because the files are there in the same place on the HD (sd1 in my case).

    Grub did not stop working once I formatted C: and the 100MB partition, only the Windows7 entry in GRUB, the rest was OK because the other partitions were untouched.

    When I restored the 100MB partition at first, (without following BFK's indications) the files came back to sda1, so the entry became functional again. This happens because GRUB is looking for certain files in sda1, and at fisrt they were deleted, but later they came back there so it could run them again. It's not a matter of the letter, as GRUB does not look for E:\Whateverfilesitneeds but rather sda1/whaterverfilesitneeds.

    By wiping or formatting a partition, you change its content, not its position, so if you put the filesystem and the files back there GRUB detects and runs them. But if you change the position of the partition, GRUB won't be able to boot Windows unless you tell it to look for them where they are now.

    My guess is that Windows' bootloader works differently, maybe it does look for a letter, and if you remove it, it won't be able to find the partition.

    Short explanation: the way Linux maps the drive differs from the one used in Windows. Win uses drive letters, whereas Linux uses something else. If you change drive letters you screw Windows' bootloader but not GRUB. If you change partition position you screw GRUB.

    Correct me if I'm missinformed.
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  8. Posts : 22,814
    W 7 64-bit Ultimate
       #28

    Makes sense to me and a very good explanation, thanks!
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  9. mjf
    Posts : 5,969
    Windows 7x64 Home Premium SP1
       #29

    M R said:

    My guess is that Windows' bootloader works differently, maybe it does look for a letter, and if you remove it, it won't be able to find the partition.
    My understanding was that the BIOS passes control over to the partition identified as active (not by partition letter). The boot manager and BCD store provide the location for loading the nominated operating system.
    eg. C:\windows\system32\winload.exe
    It is at this stage the partition drive letter is important.
    It could be D:\windows........etc to load say Vista.

    At least this was my understanding.
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  10. Posts : 84
    7 home premium 64 bit
       #30

    Hi, I am interested in having a dual boot system with linux. If you are worried about the system becoming messed up due to the booting issue some people face I was told on another forum to do this. I have not tried it yet but may be an option for laptop owners that can't install 2 hd's. Credit goes to Gezza. This is for PCLinuxOS not sure but should work with other versions.

    I have used used a usb stick (about 2GB+) to get over this problem.
    I have 64 bit win7 on a laptop and decided not to grub that system
    So plug in the usb stick, boot PCLInuxOS x.x and install it
    At the partitioning point, pick the usb stick as /boot and at the end select the usb stick as the booting device.
    Now without the stick in Win7 boots and with the stick in pclos boots.
    Just make sure the boot order is CDROM first then usb device then hard drive.
    It works very well
    Gezza
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