how to make a grub floppy or cd

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how to make a grub floppy or cd

Postby archp2008 on Mon Jul 27, 2009 11:28 am

Hello,

Can someone please point me to a guide to creating a bootable grub floppy or cd (or just a disk that could restore my current bootloader if it should get corrupted) I am using Mint 7. I have succeeded in mounting and saving to a floppy but gfloppy gives writing errors. I have tried a few other guides not specific to Mint that have not got me past the mounting stage.
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Re: how to make a grub floppy or cd

Postby lagagnon on Mon Jul 27, 2009 11:53 am

http://www.supergrubdisk.org/

However, when I just tried that website it appears to be broken at the moment....but at any rate you need "Super Grub Disk".
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Re: how to make a grub floppy or cd

Postby archp2008 on Mon Jul 27, 2009 7:10 pm

Thanks for that. The link was ok when I tried it. I installed an image to a floppy for Windows no problem. It booted into Mint. I was hoping that it would boot into my multiboot loader that Mint had generated. Perhaps I don't understand how to use the boot floppy.
I tried to install an image to a floppy in Linux. I renames the download "floppy.img" I used this path but got this result:

arch@arch-desktop ~ $ dd if=/Desktop/floppy.img of=dev/fd0
dd: opening `/Desktop/floppy.img': No such file or directory
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Re: how to make a grub floppy or cd

Postby lagagnon on Mon Jul 27, 2009 8:06 pm

You missed part of the correct file pathname. The Desktop directory is within /home/yourusername so the correct path is:

/home/yourusername/Desktop/floppy.img
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Re: how to make a grub floppy or cd

Postby archp2008 on Mon Jul 27, 2009 8:21 pm

Thanks but same result:

arch@arch-desktop ~ $ dd if=/home/arch/Desktop/floppy.img of=dev/fd0
dd: opening `dev/fd0': No such file or directory
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Re: how to make a grub floppy or cd

Postby lagagnon on Mon Jul 27, 2009 9:25 pm

That should be fd0 not fdO and you must have a diskette in the drive.
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Re: how to make a grub floppy or cd

Postby archp2008 on Mon Jul 27, 2009 10:16 pm

In the process of using the terminal and trying to get the floppy formatted, I received the message that I needed to install fdutils. After doing that, gfloppy became available and worked properly. I then used a section of this link: http://www.syrlug.org/contrib/grublinux.html to successfully backup my MBR which displays the menu.lst that lists all the OS's by booting from the floppy. I'm delighted to have this working as now I can load any OS on my system even if there is damage to the hard drive MBR. I guess this is basically what I needed. I presume this floppy can also be used to restore the MBR and menu.lst. I haven't read that far yet. I'm surprised that I have to manually mount the floppy each time I boot into Mint. Is there a fix for that issue?
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Re: how to make a grub floppy or cd

Postby lagagnon on Mon Jul 27, 2009 10:50 pm

Instead of messing with /etc/fstab to automount why not just place a floppy icon on your desktop so you have easy access to it when you want?
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Re: how to make a grub floppy or cd

Postby Fred on Tue Jul 28, 2009 12:33 am

archp2008,

I am not quite clear on what your purpose is for doing this but let me point out a couple of things.

1) The first 512 byte sector contains the MBR, (Master Boot Record), and the MPR, (Master Partition Record). This 512 byte sector is often incorrectly called the MBR. Actually the MBR is contained in the first 446 bytes. The last 66 bytes are some flag bits and the MPR.

2) If you make an install and need to use your backup as you have done it, you will wipe out your partition table. It will be put back like it was before you made your new install, wiping out your new install in the process.

I would suggest that you use bs=446 for one file and bs=512 for another file. You can then choose to replace just the MBR or the MBR and MPR depending upon what you want to accomplish at the time.

I presume this floppy can also be used to restore the MBR and menu.lst.

If you have done what I think you have done, you will be able to restore your MBR/MPR, but not your /boot/grub/menu.lst. The menu.lst isn't resident in the first 512 byte sector.

Just a couple thoughts. :-)

Fred
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Re: how to make a grub floppy or cd

Postby archp2008 on Tue Jul 28, 2009 10:30 am

lagagnon wrote:Instead of messing with /etc/fstab to automount why not just place a floppy icon on your desktop so you have easy access to it when you want?


So far I have only been able to do that by mounting the floppy manually. Is there another way to put that floppy icon there?
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Re: how to make a grub floppy or cd

Postby archp2008 on Tue Jul 28, 2009 10:46 am

I am sorry that some of this information is a bit above my skill level. As far as my purpose for making a grub backup is so that I would be able to restore the full bootloader as it now exists, for all the operating systems, This is if it ever became erased or corrupted. With regard to your item 2) the writer of the article I tried to follow suggested repeating this backup process before and after installing a new operating system. He didn't mention doing this after ordinary installs, though. I would only use this backup, of course, if I had no other way of accessing an operating systems. I do not understand what is meant bs=446 for one file and bs=512 for another file and how to use that. What is important to me is that I am able to restore the full menu.lst even if I can't boot into Mint (the OS that wrote the menu.lst). As I mentioned earlier, when I boot into the floppy recovery disk and I select the first option of the first partition it just boots Mint directly. I don't see that full listing. Please point me to an appropriate "how to" for making a disk that can load and/or restore the full bootloader. Thanks.

Fred wrote:archp2008,

I am not quite clear on what your purpose is for doing this but let me point out a couple of things.

1) The first 512 byte sector contains the MBR, (Master Boot Record), and the MPR, (Master Partition Record). This 512 byte sector is often incorrectly called the MBR. Actually the MBR is contained in the first 446 bytes. The last 66 bytes are some flag bits and the MPR.

2) If you make an install and need to use your backup as you have done it, you will wipe out your partition table. It will be put back like it was before you made your new install, wiping out your new install in the process.

I would suggest that you use bs=446 for one file and bs=512 for another file. You can then choose to replace just the MBR or the MBR and MPR depending upon what you want to accomplish at the time.

I presume this floppy can also be used to restore the MBR and menu.lst.

If you have done what I think you have done, you will be able to restore your MBR/MPR, but not your /boot/grub/menu.lst. The menu.lst isn't resident in the first 512 byte sector.

Just a couple thoughts. :-)

Fred
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