On Sat, 14 Apr 2012 05:32:01 -0500 Dale <rdalek1...@gmail.com> wrote:
> Gregory Shearman wrote: > > In linux.gentoo.user, Dale wrote: > >> I have ran into a issue here. I copied everything over to sdb, my > >> temp drive. When I try to boot it, it still boots from sda which > >> is the primary drive. I can not get it to boot from the copy. I > >> did update the fstab file to point to the new sdb partitions, I > >> use labels for that and they have different names. I also edited > >> grub and told it root was sdb2. When I boot, everything mounted > >> is sda. > > > > Did you actually install grub onto your MBR by either: > > > > # grub-install --no-floppy /dev/sdb > > > > or > > > > # grub > > > > grub> root (hd1,0) > > grub> setup (hd1) > > grub> quit > > > > ------------------------------------------------------------------------- > > > > You didn't actually write down these steps. Are you assuming that we > > know you've done that? > > > > > In the past, I never had to install grub to sdb. As long as grub is > installed to one drive, I can boot a OS from any drive. I did this > when I used to have Mandrake and Gentoo installed. I had Mandrake > installed on sda and Gentoo on sdb. I only had one /boot partition > which was on sda1. It had the kernel for both Mandrake and Gentoo in > it and sda1 was used for both. > > So, has something changed that if I want to boot from a second drive I > have to install grub to its MBR first? When the BIOS finishes and > loads grub, doesn't it always load from the first drive? If that is > true, doesn't it ignore the MBR on the second drive? It can't load > both MBRs right? Yes, if you want to boot from another drive, that drive needs to have a usable MBR (or GPT equivalent). The BIOS (or UEFI) dictates which MBR to load first, and GRUB doesn't come into it until BIOS found it and loaded it. This is usually done in the "boot sequence" config option in BIOS, although it can be temporarily overridden at boot time by pressing a suitable key. > This isn't making sense. I have done this many times in the past with > no problems but now something is different. I need help figuring out > what. There are many ways this can go wrong. Most probably BIOS boot loading sequence has changed (e.g. if you plug in a USB stick and save boot sequence where the USB stick is tried first, then what happened when you remove the stick and reboot is anybody's guess, because the BIOS will try to outsmart you in guessing what that invalid first boot device should have been). Or maybe you had /dev/sdb disk as the first boot disk all along, the previous absence of a bootloader means BIOS tried the next one silently... My own safety net is to have /dev/sda1 and /dev/sdb1 pretty much the same, except the grub.conf has a difference of a useless title line to indicate which disk it was. > Dale > > :-) :-) > Kerwin.
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