Polytropon wrote:
> On Thu, 15 Oct 2009 14:42:24 -0400, PJ <af.gour...@videotron.ca> wrote:
>   
>> But sysinstall will overwrite all the info on the disk and that defeats
>> the whole purpose of the exercise.
>>     
>
> If you only change a slice's state and add an MBR, it won't
> do anything to the data inside the slice.
>
>
>
>   
>> What complicates matters is the use of GAG as boot manager.
>>     
>
> Hmmm... I'm not familar with that, nor have I ever heared of
> it.
>
>
>
>   
>> If I select
>> to boot from ad4 and the boot is from ad12, then there is something
>> wrong.
>>     
>
> Check /etc/fstab as suggested. Furthermore, check what GAG
> actually does - just to be sure it boots the correct device.
> I always assumed that you use the standard MBR which does,
> as I explained, simply boot the first "active" slice on the
> first disk it finds. Maybe GAG acts differently.
>
>   
Gag is really about the simplest you can find... it is installed on the
main drive that is selected by bios and it works from there. I have
found it to be quite safe and reliable. Only difficulty is sometimes to
figure ;out what dist it is booting from but that can be worked out be
trial and error. I've tried the rest, this is the best KISS.
>
>   
>> It indicates to me that the mbr is loading the wrong disk.
>>     
>
> In this case, it's good to read how booting works. MBR, and
> bootN, the FreeBSD loader and the kernel own specified points
> in this race. :-)
>
>
>
>   
>> I noticed this when trying to boot a disk on my other computer... it was
>> looking for ad12 when there was no ad12 installed.
>>     
>
> "Who" was looking for ad12? Was it at the "boot>" or the "Ok"
> prompt?
>   
the boot... it could be seen in the onscreen mesages... and then the
boot oviously failed...
>
>
>   
>> I found that strange,
>> but then I recalled thatManolis Klagias had warned about something of
>> the sort. Now, I'll have to sort that out.
>>     
>
> You have to be entirely sure that the booting process works as
> intended. The easiest way to ensure this is to first use only
> one disk at once in the system. There are different stages where
> things can get messed up, such as the loader or /etc/fstab.
> They have to match the situation.
>
> As a sidenote, GEOM supports labelling partitions so it does not
> matter anymore if, for example, a / partition is ad4s1a or ad12s1a.
> There's a section in the handbook that illustrates how to get rid
> of device names in /etc/fstab.
>   
I noticed that but have not yet had the opportunity to look into it.

The fstab did cure the problem and showed some of the pitfalls one can
encounter. After fixing the fstab, the boot did not complete because the
fstab from the source disk had anextra partition (/backups) which were
not present in the original ad4 disk. But that was easiily fixed by
simply removing the fstab entry for that  /backups partition. Now it
works fine.
>
>
>
>
>   

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