[Dar-discussions] Dar inconsistency on differential backup based on catalogue file

[T o n g <mli...@ya...>]

Hi Denis, 

I decided to still follow up here because it is more a bug report now.

To recap all related info first:

 $ dar -l /path/to/da-name_2009-12-11-cat | head -15
  [ . . . ]
 [InRef]       [-----]   -rwxrwxr-x   tong       tong    8510    Fri Jan  4 13:47:05 2008        inet/web/larve.2006.add-to-social-bookmarking-services.htm
 [InRef]       [-----]   -rwxrwxr-x   tong       tong    12385   Fri Jan  4 00:00:00 2008        inet/web/sb.zip
 [InRef]       [-----]   -rwxrwxr-x   tong       tong    199     Fri Jan  4 13:47:17 2008        inet/web/11getlog.lst
  [ . . . ]

 $ ls -l inet/web/larve.*.htm inet/web/sb.zip inet/web/11getlog.lst
 -rwxrwxr-x 1 tong tong   199 2008-01-04 09:47 inet/web/11getlog.lst
 -rwxrwxr-x 1 tong tong  8510 2008-01-04 09:47 inet/web/larve.2006.add-to-social-bookmarking-services.htm
 -rwxrwxr-x 1 tong tong 12385 2008-01-03 20:00 inet/web/sb.zip

I.e., all files are time-shifted by exactly 4 hours. Here's what happened:

  $ dar -e -v -R /path/to/d_arch -c /path/to/da-name_2010-09-05-diff -A /path/to/da-name_2009-12-11-cat -s 10M
  Extracting contents of the archive...
  Adding file to archive: /path/to/pwd/db
  Adding file to archive: /path/to/pwd/db/dict
  Adding file to archive: /path/to/pwd/dev
  Adding file to archive: /path/to/pwd/fun
  Adding file to archive: /path/to/pwd/fun/games
  Adding file to archive: /path/to/pwd/inet
  Adding file to archive: /path/to/pwd/inet/lan
  Adding file to archive: /path/to/pwd/inet/web
  Adding file to archive: /path/to/pwd/inet/web/larve.2006.add-to-social-bookmarking-services.htm
  Adding file to archive: /path/to/pwd/inet/web/sb.zip
  Adding file to archive: /path/to/pwd/inet/web/11getlog.lst
  Adding file to archive: /path/to/pwd/inet/agent
  Adding file to archive: /path/to/pwd/inet/email
  [ . . . ]

I.e., all files are put again into the differential backup.

  $ dar -e -v -R /path/to/d_arch -c /path/to/da-name_2010-09-05-diff -A /path/to/da-name_2009-12-11-cat -s 10M -H5
  Extracting contents of the archive...
  [ . . . ]
  Adding file to archive: /path/to/pwd/inet/web
  Adding file to archive: /path/to/pwd/inet/web/larve.2006.add-to-social-bookmarking-services.htm
  Adding file to archive: /path/to/pwd/inet/web/11getlog.lst
  Adding file to archive: /path/to/pwd/inet/agent
  Adding file to archive: /path/to/pwd/inet/email
  [ . . . ]

I.e., having add '-H5'/'-H6' (ideally -H4 should be enough) to the dar
command line, dar only considers the 'sb.zip' file to be backed
up before, and still add the other 2 files.

> What's happening? How can I do further investigation?

,-----
| there is an easy way to know why dar saved a file for differential
| backup, it is to use the archive of reference and make a diff (dar -d)
| against the fileystem you want to backup. For each file that differs
| between archive and fileystem, dar will output what causes the difference.
`-----

OK, here it goes:

  $ /usr/bin/dar -v -R /path/to/d_arch -d /path/to/da-name_2009-12-11-cat
  [ . . . ]
  OK   /path/to/d_arch/inet/lan
  OK   /path/to/d_arch/inet/web
  OK   /path/to/d_arch/inet/web/larve.2006.add-to-social-bookmarking-services.htm
  OK   /path/to/d_arch/inet/web/sb.zip
  OK   /path/to/d_arch/inet/web/11getlog.lst
  OK   /path/to/d_arch/inet/agent
  OK   /path/to/d_arch/inet/email
  [ . . . ]

I.e., 'dar -d' thinks and reports that all 3 files are OK, and
shouldn't be put into the differential backup, even the -Hx
parameter is NOT given. There is sure some inconsistency here. 

FYI, I've also executed the actual backup command without the '-e'
parameter, and the result is same. I.e., the behaviour is
consistent w/ or w/o '-e'.

Please investigate. 

PS. I don't know how easily for you to duplicate a time-zone
shifting scenario (ie, whether changing the time-zone will have immediate
affect without rebooting), but this is how it happened to me.
http://thread.gmane.org/gmane.linux.debian.user/386125/focus=386199
Long story short, the files are on vfat partitions, you get
different file time when flipping BIOS CMOS clock between UTC and
localtime. Again, hope there is an easier way for you to
duplicate a time-zone shifting scenario. 

Thanks

On Mon, 06 Sep 2010 03:21:34 +0000, T o n g wrote:

> Ok, the time-zone shifting might be the cause:

-- 
Tong (remove underscore(s) to reply)
  http://xpt.sourceforge.net/techdocs/
  http://xpt.sourceforge.net/tools/