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Thread: GRUB Error 15

  1. #11
    Join Date
    Jun 2008
    Location
    Atlanta, Georgia, USA
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    2,429

    Default Re: GRUB Error 15

    Quote Originally Posted by Budgie2 View Post
    Not as much help as you suggest. just 2 entries:-
    setup --stage2=/boot/grub/stage2 (hd,0) (hd0,1)
    setup --stage2=/boot/grub/stage2 (hdo,1) (hd0,1)

    No mention of stage 1 which does however appear in /boot/grub along with various variants *stage1.5.

    How can I check whether grub is in mbr or not. By the way the drive is hardware RAID so I assume BIOS sees it as single drive with mbr as though it were a single disk.
    Au contraire. The grub setup command is actually a macro for the grub install command, and with both the primary file being used is stage1. In the syntax above - which you mis-typed so I can't be positive exactly what was done - stage1 was installed twice, once to "(hd,0)" which could be the first partition's boot sector (i.e., (hd0,0)) or the MBR ((hd0)). Secondly installed to "(hdo,1)" which appears to be (hd0,1), i.e., the boot sector of the second partition on the first disk. I would therefore guess that the first setup line was (hd0,0), the matching partition in the array (?). Both stage1's are pointed to the same location to find the grub stage2 loader, i.e., the /boot directory on (hd0,1).

    Stage_1.5 files are typically used when grub is installed to the MBR. Stage1 cannot read a file system, and so will not be able to find stage2 on its designated partition (that partition has its location embedded as a pointer into stage1 at installation, so the partition can be found but not read). The sectors immediately following the MBR are typically vacant; this is where stage_1.5 will be put. So stage1 in the MBR calls stage_1.5 (the shell will have chosen the applicable 1.5 to match stage2's file system). When grub is installed to a partition boot sector, stage_1.5 is not needed because the location of stage2 is in the sector's bios partition block enabling stage1 to find it without help.

    To look at the contents of the MBR, from the command line as root (being extremely careful, a typo can be disastrous here):

    Code:
    dd if=/dev/<disk> of=mbr bs=512 count=1
    xxd mbr
    Where <disk> is the name of the disk, e.g., sda (note: not a partition like sda1, but the whole disk, as the MBR is in the first sector of the disk before any partitions, which typically begin at sector 63).

  2. #12
    Join Date
    Jan 2009
    Location
    USA
    Posts
    21

    Default Re: GRUB Error 15

    I have the solution to the problem I originally posted. I was reading this article on the opensuse web:

    Bugs/grub - openSUSE

    I re-created my RAID 5 array but took the option under "Maximum boot partition" "Enable 8GB Maximum." Suse installed without issue and sailed through the GRUB portion without hiccup or delay. My RAID 5 array consists of 6 - 500G SATA disks.

    Thanks to all that provided feedback. I will definitely use the forums on opensuse again, great place for knowledge sharing. I am going to setup Xen next and build some VMs. Onward and upward!

  3. #13
    Join Date
    Jun 2008
    Location
    Atlanta, Georgia, USA
    Posts
    2,429

    Default Re: GRUB Error 15

    Quote Originally Posted by gmarchant View Post
    I have the solution to the problem I originally posted. I was reading this article on the opensuse web:

    Bugs/grub - openSUSE

    I re-created my RAID 5 array but took the option under "Maximum boot partition" "Enable 8GB Maximum." Suse installed without issue and sailed through the GRUB portion without hiccup or delay. My RAID 5 array consists of 6 - 500G SATA disks.

    Thanks to all that provided feedback. I will definitely use the forums on opensuse again, great place for knowledge sharing. I am going to setup Xen next and build some VMs. Onward and upward!
    Fascinating. So the "8GB maximum boot partition" setting was in the utility that creates the array? That would effectively eliminate the need for LBA, i.e., CHS geometries are used. Does this mean that the boot sector and boot files are isolated to one of the disks rather than being striped?

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