On 20100313_095320, Tom H wrote: > >> I believe a UUID is generated when the partition is "formatted", either > >> with > >> mkfs or mkswap. > > > I confirm - just tried shrinking and growing back an extfs. UUID is left > > untouched (as expected); that Mint article is BS or just obsolete. > > I have never come across the problem described by the Mint link.
I have seen a UUID change in a way that disrupts my work: When I install a 2nd/3rd distrib on a HD, I have made it a practice to set up fstab so the existing distrib are mounted automatically. Repeated use leads to all functioning distrib to be crosslinked. But when a distrib must be reinstalled because something drasticly wrong happened, or whatever, access to that replacement distrib in all the older distrib is broken because the UUID of the partition is changed. This is not a killer objection for me. But it is a use case expample that belies some broad claims about UUIDs. If there were a place on every partition where a UUID of the partition could be recorded, and if the partitioning software could be trained to preserve that record whenever the partition is simply wiped in preparation for a reinstall, then ... maybe this use case would behave more to my liking. But I am aware that there are a lot of individual requirements for partition identifiers, so I hesitate to advocate this proposal in this most simple form. As I say, I understand enough about the scheme that I think I can live with it in its current form. Also. There seems not to be a standard algorithm for computing UUID bit strings. Different developer/users of UUID ideas seem to be free to choose what algorithm and what input data they use to get their UUIDs. So, the actual behavior of UUID technology in Debian may change over time. Future versions of Debian may silently change to address old problems (and to introduce new problems). > > The closest is having swap's UUID change when installing a 2nd/3rd > distrib on the same HD. > > Someone said earlier > > "I can't imagine any case where an filesystem UUID change "by the > face", I think this is not possible if you didn't execute any > filesystem command to do it." > > and cannot but +1 the comment because the UUID is held in a > partition's superblock. > My original post has generated a lot of very interesting discussion. UUIDs are no longer so mysterious. I think that there is more work to be done, but I have no good ideas to pursue and I have reached my attention span limit. I don't want to post with a subject line "Solved", but it is true that I want to stop discussing this. Thanks to all. -- Paul E Condon pecon...@mesanetworks.net -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/20100313160128.gb2...@big.lan.gnu