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  Creating a Dual-Boot Windows XP and Ubuntu Laptop
Subject:   got an error
Date:   2006-07-11 19:01:18
From:   kfarnham
Response to: got an error

octathlon, here is a page that describes what GRUB Error 18 means:


Briefly, GRUB Error 18 means "Selected cylinder exceeds maximum supported by BIOS" and it can be fixed by "creating a boot partition at the beginning of the disk that is completely within the first 1023 cylinders of the harddrive."

It's a little bit difficult to diagnose since I don't know all the details of your system. Do you have two different physical disk drives on your system? That's what I'm thinking based on your "slave drive" and "master" description. If that's the case, then is your first partition on the slave drive larger than 1023 cylinders in size? If so, that's the problem. You'll have to repartition that slave drive to get the size of the first partition down to 1023 cylinders or lower.

Feel free to repost here, or send an email to me. But posting here might help future readers who come across the same problem (GRUB Error 18 is apparently pretty common)...

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  • got an error
    2006-07-11 22:31:23  octathlon [View]

    Thanks very much for that link and the info. The first partition on the slave (hdb) is a small primary partition intended for /boot (cyl 1 to 13), however I didn't specify that when installing Ubuntu, so it put /boot under its / partition, which is at a cylinder greater than 1023 (it's at 2820).

    However, I don't think that's the problem because Ubuntu overwrote the MBR on the primary (Windows) drive (without asking me!) and it boots just fine from there. It seems like I should get the same error if it was a cylinder limit issue (this is a Pentium 4, so it should be new enough not to have that problem, I would think).

    I was trying to implement the article's technique so that I would be able to restore the MBR to Windows, so that the Windows drive would be independent of the Linux drive. I tested it by by choosing Windows from the Ubuntu menu, then choosing Ubuntu from the Windows menu, which I had set up according to the article.

    Since I have the partition available, I could test by installing the Ubuntu bootloader stuff to it, but I'm not sure how to do that (grub-install and copy all /boot files, I guess). I'll have to read more about GRUB before I try anything else.