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On Sat, 14 Apr 2012 05:32:01 -0500 |
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Dale <rdalek1967@×××××.com> wrote: |
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|
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> Gregory Shearman wrote: |
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> > In linux.gentoo.user, Dale wrote: |
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> >> I have ran into a issue here. I copied everything over to sdb, my |
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> >> temp drive. When I try to boot it, it still boots from sda which |
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> >> is the primary drive. I can not get it to boot from the copy. I |
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> >> did update the fstab file to point to the new sdb partitions, I |
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> >> use labels for that and they have different names. I also edited |
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> >> grub and told it root was sdb2. When I boot, everything mounted |
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> >> is sda. |
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> > |
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> > Did you actually install grub onto your MBR by either: |
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> > |
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> > # grub-install --no-floppy /dev/sdb |
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> > |
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> > or |
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> > |
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> > # grub |
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> > |
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> > grub> root (hd1,0) |
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> > grub> setup (hd1) |
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> > grub> quit |
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> > |
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> > ------------------------------------------------------------------------- |
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> > |
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> > You didn't actually write down these steps. Are you assuming that we |
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> > know you've done that? |
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> > |
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> |
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> |
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> In the past, I never had to install grub to sdb. As long as grub is |
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> installed to one drive, I can boot a OS from any drive. I did this |
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> when I used to have Mandrake and Gentoo installed. I had Mandrake |
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> installed on sda and Gentoo on sdb. I only had one /boot partition |
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> which was on sda1. It had the kernel for both Mandrake and Gentoo in |
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> it and sda1 was used for both. |
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> |
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> So, has something changed that if I want to boot from a second drive I |
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> have to install grub to its MBR first? When the BIOS finishes and |
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> loads grub, doesn't it always load from the first drive? If that is |
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> true, doesn't it ignore the MBR on the second drive? It can't load |
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> both MBRs right? |
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|
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Yes, if you want to boot from another drive, that drive needs to have |
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a usable MBR (or GPT equivalent). |
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|
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The BIOS (or UEFI) dictates which MBR to load first, and GRUB doesn't |
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come into it until BIOS found it and loaded it. This is usually done |
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in the "boot sequence" config option in BIOS, although it can be |
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temporarily overridden at boot time by pressing a suitable key. |
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|
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> This isn't making sense. I have done this many times in the past with |
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> no problems but now something is different. I need help figuring out |
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> what. |
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|
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There are many ways this can go wrong. Most probably BIOS boot loading |
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sequence has changed (e.g. if you plug in a USB stick and save boot |
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sequence where the USB stick is tried first, then what happened when |
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you remove the stick and reboot is anybody's guess, because the BIOS |
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will try to outsmart you in guessing what that invalid first boot |
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device should have been). Or maybe you had /dev/sdb disk as the first |
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boot disk all along, the previous absence of a bootloader means BIOS |
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tried the next one silently... |
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|
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My own safety net is to have /dev/sda1 and /dev/sdb1 pretty much the |
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same, except the grub.conf has a difference of a useless title line to |
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indicate which disk it was. |
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|
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> Dale |
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> |
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> :-) :-) |
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> |
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|
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Kerwin. |
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