Re: Grub2 with multiple Debians
On Fri, 14 Sep 2012 23:06:42 +0200, lee wrote:
> Hendrik Boom <hendrik@topoi.pooq.com> writes:
>
>> It has been my practice when upgrading between Debian releases to make
>> bootable copies of the OS partitions on my hard drive so that if things
>> go badly wrong I still have a bootable system.
>
> How did you make such copies?
Usually by tar piped into untar. Sometimes supplemented by rdiff-copy in
case anything changed during the copy. This makes it easy to change the
file system while I'm at it. Occasionally useful. No, I didn't use dd,
or anything that might co[y the UUID.
>
>> This wprked fine with LILO and GRUB 1, where I was in control of
>> configuratino files and could explicitly specify which root partitions
>> went with which boot partitions/
>>
>> But when installing grub2 to an MBR. all this is automated. It looks
>> around on the available disks and figures out shoch partition goes with
>> which.
>>
>> Of course, after I've made my copy (with slight changes to /etc/fstab)
>> I have two nearly identical sets of partitions, so it may be tricky to
>> tell them apart. Is grub2 clever enough to figure it all out anyway?
>> And what data does it use to this end? (so I can make sure it's right!)
>
> Are you referring to grub figuring it out when booting or to grub
> figuring it out while it's being installed? (In any case, I don't know
> any of the answers ...)
Presumably while installing grub. WHile booting, grub2 has precious few
decisions to make -- it's pretty well all scripted from the configuration
file.
>
> There needs to be a way for grub to figure out where to look for its
> configuration. Perhaps this information is stored in the MBR when
> installing grub. In that case, you would have a problem when grub
> cannot find its configuration there anymore (like because the
> partitioning has changed) and maybe a problem if it finds the wrong
> configuration.
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