Date: Thu, 16 Aug 2012 15:15:42 +0400 From: Andrey Zonov <andrey@zonov.org> To: Daniel Braniss <danny@cs.huji.ac.il> Cc: Garrett Cooper <yanegomi@gmail.com>, freebsd-hackers@freebsd.org Subject: Re: GPT boot from 2nd. disk fails Message-ID: <502CD65E.4010900@zonov.org> In-Reply-To: <E1T1uAI-0008mU-OK@kabab.cs.huji.ac.il> References: <E1T1YwR-000Gfo-O4@kabab.cs.huji.ac.il> <CAGH67wRf9gpJen%2BVC6OzePLDwWE3dC_T9Ve6DPKs=12N6VuMMA@mail.gmail.com> <201208151116.21461.jhb@freebsd.org> <E1T1uAI-0008mU-OK@kabab.cs.huji.ac.il>
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On 8/16/12 11:06 AM, Daniel Braniss wrote: >> On Wednesday, August 15, 2012 4:46:28 am Garrett Cooper wrote: >>> On Wed, Aug 15, 2012 at 1:27 AM, Daniel Braniss <danny@cs.huji.ac.il> wrote: >>>> hi, >>>> this host has to disks: >>>> sa0> gpart show >>>> => 34 976773101 ada0 GPT (465G) >>>> 34 128 1 freebsd-boot (64k) >>>> 162 4194304 2 freebsd-ufs (2.0G) >>>> 4194466 33554432 3 freebsd-swap (16G) >>>> 37748898 939024237 4 freebsd-zfs (447G) >>>> >>>> => 34 976773101 ada1 GPT (465G) >>>> 34 128 1 freebsd-boot (64k) >>>> 162 4194304 2 freebsd-ufs [bootme] (2.0G) >>>> 4194466 8388608 3 freebsd-swap (4.0G) >>>> 12583074 964190061 4 freebsd-zfs (459G) >>>> >>>> but no amount of magic will cause boot from the second disk, it will >> always >>>> boot from the first disk. >>>> >>>> any insights? >>> >>> Use boot0cfg -s 5 (untested with GPT disks)? >> >> Will not work with GPT disks. They use /boot/pmbr to boot, not /boot/boot0. >> >> If you can get your BIOS to explicitly boot ada1 from the start via a BIOS >> setting, that should work. Another option would be to break into gptboot's >> prompt (similar to breaking into boot2) aud typing in 'ad1p2:/boot/loader' or >> some such. If that works you should even be able to write that to >> /boot.config on ada0p2's filesystem. > > sorry, as usual my questions are a bit terse :-), > I want to switch between roots either at boot time (this is very tricky now, > since breaking into boot2 needs very fast fingers) or before reboot. > btw, it's 1:ad(0p2)/boot/loader > also, since the disks are hot swap, i can switch between them, but I realy > want to do it via software! > > the bootme trick did work, on a different host/setup and sometime ago. > > before GPT, when we had MBR, I could switch between slices/partitions either > via the menu or via boot0cfg, so maybe I should go back to mbr. > You can erase boot record of the first disk, then your BIOS will try to use second one. Be careful, some BIOS'es try only first disk. -- Andrey Zonov
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