on 9-22-2008 11:06 AM MHR spake the following: > On Mon, Sep 22, 2008 at 10:08 AM, Scott Silva <ssilva-m4n3GYAQT2lWk0Htik3J/w at public.gmane.org> wrote: >> Grub boot code is in the mbr so it loads. If it can't find the stage 2 it >> usually quietly dies. I believe it has to load stage 1 to have enough code >> to actually give error messages. The mbr is just too small to get all the >> code into. So changing drives also changed the bios disk order on your >> system, and grub got confused. >> > > I sympathize (I'm confused, too). > > I can't swear to it, but I'm pretty sure I had rebooted several times > after changing the boot drive and the boot drive order, all without a > hitch. Then this happened. > > I can swear (now) that I have rebooted several times since recovering, > so if I muddled through this correctly, you're saying that it > shouldn't happen again as long as I don't change the drive order > again, right? > > One of the things that I found rather irritating in all this was the > utter lack of clarity provided in both the man pages for grub and > grub-install, and the info pages (which are supposed to be more in > detail but are not, really). How do I know which disk is which from > grub's p.o.v.? There is no command to list the drives, and I wound up > using the geometry command and my personal knowledge of what those > were supposed to be to figure out which one grub thought was which, > and even that made no sense because what grub saw as hd0 was my > /dev/hda drive (which is not the boot drive) and hd2 was my /dev/sda, > which _is_ the boot drive. Or do the drive designations change once > the system is up? (I.e., in my grub.conf, the boot drive is hd0, but > when the system comes up, it's hd2.) > > I've looked through the documentation for grub at > http://www.gnu.org/software/grub/manual/html_node/index.html and this > particular ideosyncrasy is not clear. > > Thanks, all. > > PS: My apologies for the earlier html post - I sent that via Evolution > from home, and apparently it is not configured for text-only by > default (which I completely forgot). > > mhr It is more common with the systems that have pata and sata interfaces on them. The bios first starts its int13 code and maps drives in a certain order, then when linux starts, its drivers load and everything re-maps again. If you have hard drives on both, it is a crapshoot sometimes. The newer kernels have supposedly moved the old ide code into the base sata drivers, so someday all the drives will show up as sd?. http://linuxgazette.net/141/anonymous.html http://linux.knightnet.org.uk/2008/01/more-on-grub-bug-with-mixed-pata-and.html -- MailScanner is like deodorant... You hope everybody uses it, and you notice quickly if they don't!!!! -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 250 bytes Desc: OpenPGP digital signature URL: <http://lists.centos.org/pipermail/centos/attachments/20080922/5508b4e0/attachment-0005.sig>