On Tue, 31 Jan 2006, Jon LaBadie wrote: > On Tue, Jan 31, 2006 at 10:56:13AM +0100, Geert Uytterhoeven wrote: > > I saw a similar thing when the disk of my backup server died last month. > > The machine ran Debian testing, and I used an Ubuntu Live CD (the Knoppix I > > had > > lying around didn't support SATA) to do the restore. > > > > After the restore, some services didn't work because some configuration > > files > > were owned by the wrong user. > > > > I ended up comparing the uids and gids in /etc/passwd and /etc/group on the > > restored image and on the Ubuntu Live CD, and for all differences, manually > > verifying all uids and gids of all restored files and directories. > > Fortunately > > this took much less time than expected :-) > > > > I noticed one very strange thing though: uids and gids were not changed in a > > consistent way: some files had the incorrect uid or gid from Ubuntu, while > > other related files that should have the same uid/gid had the one from the > > original system. So sometimes uids/gids were remapped during restore, but > > not > > always... > > My understanding, subject to correction, is that by default guntar > restores by trying to match text names (user and group) between the > archive and the recovery system. If a match is found, then the > restore is to the numeric uid/gid of the recovery system, thus > matching the names, but not the necessarily the numeric ids in the > archive. If matching text names are not found, then the archive's > numeric ids are used.
Exactly my understanding as well. > So you could easily get a real hodge-podge of names and numeric ids > by recovering to a different system. > > Archived System Recovery System Result of Recovery > name id # name id # name id # > > AAA 111 AAA 111 AAA 111 > BBB 222 BBB 234 BBB 234 > CCC 333 (no CCC) (no 333) (none) 333 > DDD 444 (no DDD) (EEE is 444) EEE 444 > > Note, 3 of the 4 cases result in a recovery that doesn't match the > originally archived system. May or may not be what was wanted. But as soon as /etc/passwd and /etc/group have been restored from backup as well and you boot from the restored medium, CCC and DDD become correct again, right? But this is not what I saw. Some files that should be owned by user BBB had uid 222, while others had 234. It was not consistent. > If the --numeric-owner option was used, only the second case would > change, the recovered result using an id of "222" rather than "234" > with a text name of either "none" or whatever name matchs id "222". Which is what you want (assumed you backup OS files, instead of doing a clean reinstall of the OS)... Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [EMAIL PROTECTED] In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds