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Re: drive names and UUIDs, was Re: Intresting dd fsck grub uuid fstab action




On Saturday 03 June 2017 11:02:54 Fungi4All wrote:

> -------- Original Message --------
> From: deblis@xxxxxxxxxxxxxxxxx
> To: debian-user@xxxxxxxxxxxxxxxx
>
> On Thu 01 Jun 2017 at 12:24:28 (-0400), Fungi4All wrote:
> > Why don't just skip all this that we are in perfect agreement with
> > and go to the juicy part. After all uuids are unique and fstab are
> > all correct, updating-grub would mix match uuids in writing its
> > grub.cfg
> > Two uuids on the same entry! Over and over again.... till I edited
> > it out to the correct ones and it all worked. Why does everyone
> > choses to skip on this issue and keeps explaining me over and over
> > what I have well understood by now?
>
> Well, we don't have a lot of evidence. But we do have a tiny bit:
>
> Ι was waiting to see if anyone else found something like this
> significant and willing to contribute some wisdom I suspect the
> experiment would be simple.
> Let's say we make a new partition on a disk with a debian installed
> system and use dd to clone that system in the new partition (I have no
> idea whether doing this in the same disk or a second one makes a
> difference),

I don't believe that will work.  dd runs on the raw device, not to an 
artificially created "partition".

rsync OTOH, can run on a partition to partition basis.  And that should 
give you different blkid's.

> Let's say that dd copies uuid to the new partition so we 
> have two partitions with the same uuid in the same system.
> Intentionally we make the mistake and log in to the original system
> and update-grub with the conflict. Then relogin and create new uuids
> for the clone, edit ftstab and check original, then update-grub. Will
> it boot having the first root or the clone root? Then look at grub.cfg
> of the original to see if the uuids for each entry are matching or
> there is a mismatch.
> I went through the grub manual and didn't come up with an answer. It
> smells like a tiny bug or room for improvement. Also, I believe that
> when dd is used to copy something from disk to disk it should provide
> an option of whether to produce a new uuid or retain the original
> (backup, not a concurrent system).
>
> if [ x$feature_platform_search_hint = xy ]; then
> search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos3
> --hint-efi=hd0,msdos3 --hint-baremetal=ahci0,msdos3
> --hint='hd0,msdos3' UUID on sda3 XXX else
> search --no-floppy --fs-uuid --set=root UUID on sda3 YYY
> fi


Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>