[SLE] Grub and mirrored root disk
Hi, This is SUSE 10.0, with patches. I have a mirrored /boot file system (soft-RAID 1, with md). I.e., /dev/md0 is mounted at /boot, and /dev/md0 is a mirror of /dev/sda1 and /dev/sdb1. The initial setup of the mirror and of GRUB was done during the SUSE installation. After a recent kernel update, my system hang at the GRUB message and could not be booted. (I know why I postpone kernel updates until I have time to cater for the aftermath... ;-) Well, that was rather easy; I repaired it from the rescue system by repeating the GRUB setup: grub> root (hd0,0) grub> setup (hd0) grub> quit That worked, the system now boots again. Now I'm wandering if that was sufficient, because GRUB is not reinstalled on the second disk. (When the first disk fails, it shall be able to boot from the second, of course.) I have two questions: 1) Do you know if a SUSE installation does something special when GRUB is used for mirrored disks? Does it install stage1 in both MBRs or only in one MBR? 2) Independently of my first question, are there recommendations how to handle the situation? Shall I do the GRUB-setup for hd1, like I did for hd0? Thanks in advance for any opinions, Joachim -- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Joachim Schrod Email: jschrod@acm.org Roedermark, Germany -- Check the headers for your unsubscription address For additional commands send e-mail to suse-linux-e-help@suse.com Also check the archives at http://lists.suse.com Please read the FAQs: suse-linux-e-faq@suse.com
Joachim Schrod wrote:
I have two questions:
1) Do you know if a SUSE installation does something special when GRUB is used for mirrored disks? Does it install stage1 in both MBRs or only in one MBR? AFAIK, it only installs it to the first disk. Check /boot/grub/menu.lst and /etc/grub.conf.
2) Independently of my first question, are there recommendations how to handle the situation? Shall I do the GRUB-setup for hd1, like I did for hd0? That is what I have always done. I don't have a separate /boot anymore since booting a root raid1 works. And since the BIOS is designed to boot from one drive, it works fine to boot from the MBR of the first drive most of the time. One gotcha I have run into is if the boot order is changed in BIOS, it changes the order Grub sees the disks. I don't yet know what would happen on my newer motherboard that instead of booting the first disk it boot the HD in a particular order, and if drive one failed, would grub still boot from the second. So, a kernel upgrade doesn't really affect the grub install if it was done correctly in the first place. Also, I have added a second menu item that boots from the second disk when the first dies. There is a RAID1 and Grub howto out there that also explains this. You can add a fallback entry to menu.lst to auto boot the second if the first fails. HTH.
-- Joe Morris Registered Linux user 231871 -- Check the headers for your unsubscription address For additional commands send e-mail to suse-linux-e-help@suse.com Also check the archives at http://lists.suse.com Please read the FAQs: suse-linux-e-faq@suse.com
participants (2)
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Joachim Schrod -
Joe Morris (NTM)