> From: rnicholsnos...@comcast.net > To: rdiff-backup-users@nongnu.org > Date: 19/11/2012 23:54 > Subject: Re: [rdiff-backup-users] Weird behavior of rdiff-backup : > founding diffs while there isn't > Sent by: rdiff-backup-users-bounces+matthieu.rioteau=skf....@nongnu.org > > On 11/19/2012 11:19 AM, matthieu.riot...@skf.com wrote: > > > > So I think here is the key. You can see that uname is once void and once > > filled with the user name. > > It also appears that "faulty" changes can be of 2 sorts : > > - Uname was void and is now filled > > - Uname was filled and is now void > > > > Now, running a "stat" command on a file where uname is currently void (in > > rdiff mirror) correctly returns the owner name. > > > > A strange thing remains : running a rdiff-backup --compare-at-time 2B (or > > even 3B or 4B) on a folder chere files changed returns "No changes found. > > Directory matches archive data.". > > Notice that --compare-hash-at-time or --compare-full-at-time returns the > > same. > > So is it possible that documentation tells that --compare-at-time do the > > same as when a backup is runned, but that uname is actually used only for > > true backups and not for --compare option ? > > > > The last weird thing is that if I browse through the "increments/" folder, > > I will find a very small .diff file for each changed file. > > Example with the first file listed above : > > -------------------- > > hexdump -C VirtualBox.xml.2012-11-16T23\:50\:04+01\:00.diff > > 00000000 72 73 02 36 46 00 04 35 00 |rs.6F..5.| > > -------------------- > > > > But this is not the most important as preventing rdiff-backup viewing > > changes shall prevent also these increments to be stored. > > > > So question is : why are these "uname" once here and once gone ? > > > > I see 4 main differences between the working system and this one that > > could lead to that : > > - Hard drive is a RAID 1 (working system doesn't have RAID), but I don't > > think it is the reason as it is pure hardware, and there is the FS over. > > - Source partition is ext4 (working system is ext3). > > - Owners (i.e. uname) are LDAP users and LDAP server isn't on the faulty > > machine (it is on the working one). So users are not listed in the > > /etc/passwd file. > > - Kernel is 2.6 (working system is 3.2) and maybe one of the above > > characteristics (or another one) is badly managed by 2.6 kernels. > > By default, rdiff-backup tries to preserve user _names_, not numeric UIDs. > This is obviously going to be a problem if one machine is able to map > UIDs to names and the other is not. I'd look into why the faulty machine > is apparently unable to contact the LDAP server to do the mapping. You > might see if the "--preserve-numerical-ids" option masks the problem, > but, frankly, I doubt it. > > The tiny change files are basically saying, "There is no change." You > will get that any time there is a metadata-only change. That file is > required to exist if any change at all occurred. > > -- > Bob Nichols "NOSPAM" is really part of my email address. > Do NOT delete it. > > > _______________________________________________ > rdiff-backup-users mailing list at rdiff-backup-users@nongnu.org > https://lists.nongnu.org/mailman/listinfo/rdiff-backup-users > Wiki URL: http://rdiff-backup.solutionsfirst.com.au/index.php/RdiffBackupWiki
Hi Bob, I also think problem is definitely LDAP, more precisely that machine is not able to get access to LDAP server during a time lap. And I think I found the reason (actually when waking up on this morning (seems it was good to sleep on it). ;-) The 2 machines are starting their respective backup at the same hour and the one with the LDAP server is shutting it down during backup (voluntarily) to prevent partial/corrupted data backup. Thus the other machine is probably not able to resolve user names during a small time. So a good way to fix the issue will probably to postpone one the backup to an hour where I'm sure that the other one is no more running. However I think that the "--preserve-numerical-ids" option that you suggested can also do the job. So I have add it to the rdiff-backup so it will be tested during next backup. Then only I will time shift one of the backup, but if the option is well working, that will be an extra data-safety feature. When I will have test everything, I will keep you updated so all your efforts finally get an answer (you can expect it by the end of the week). :-) Here I should say I'm a little bit confused to have not think about that before posting on the mailing list (maybe it could have preserve your time)... :-| So I'm more than very thankful to you for all your complete and helpful answers. ;-) Thanks a lot, I will keep you updated very soon. PS : one small thing I can share. During investigations, I often have to analyze file_statistics....data.gz files. Thus I quickly use this practical bash line : --------------------------------------------------------------------------- user@machine:~$ (gunzip -d | gawk -F" " '{if ($0 !~ /NA$/) print $0;}' | less) < /BACKUP/FOLDER/rdiff-backup-data/file_statistics.THE_DATE.data.gz --------------------------------------------------------------------------- That will list all lines where IncrementSize is not "NA". If you remove the '~', you will get the opposite. Hope it can help someone. ;-)
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