Re: [rdiff-backup-users] Force a regression of rdiff-backup archive

[Dominic Raferd]

This must be almost a record snail-wise for a newsgroup correspondence 
(my original posting June 2009, Janne's reply Feb 2010, this reply Jan 
2011), but by way of a very belated thank you to Janne for his 
suggestion, and using his technique, I attach a bash script which 
automates the process of forcibly regressing an rdiff-backup repository.

Help is built in, just run the script without parameters to see. It does 
a single step regression, it can be run multiple times if you need to 
regress the repository back further. All the usual caveats apply.

Dominic

On 23/02/2010 10:39, Janne Peltonen wrote:
> Hi!
>
> I don't know if you solved your problem already some another way, but I thought
> it'd be nice to tell what I do in situation like this, anyway.
>
> Without looking at the source, it appears that rdiff-backup decides whether a
> regression is in order by checking whether there are two current_mirror stamps
> (one for the supposedly failed backup, the other for the previous, successful
> backup). So you can force a regression to the previous version by creating a
> new current_mirror stamp file in the destdir/rdiff-backup-data directory. (The
> file contains the word "PID", a space, and the pid of the rdiff-backup process
> that created the version, but the contents aren't that interesting in this
> case; you can just copy the existing current_mirror file.) The timestamp in the
> file name of the current_mirror file must match the timestamp of the previous
> backup, the one you want to regress to (you can only regress to the previous
> backup, don't try to skip versions).
>
> An example might be in order:
>
> --clip--
> varma:/backup/data/aulis/rdiff-backup-data# ls -ltr mirror_metadata*|tail -n2
> -rw------- 1 root root    7243 21.2. 02:49 
> mirror_metadata.2010-02-20T01:00:20+02:00.diff.gz
> -rw------- 1 root root 5453359 23.2. 12:07 
> mirror_metadata.2010-02-21T01:00:21+02:00.snapshot.gz
> varma:/backup/data/aulis/rdiff-backup-data# cp 
> current_mirror.2010-02-21T01:00:21+02:00.data 
> current_mirror.2010-02-20T01:00:20+02:00.data
> varma:/backup/data/aulis/rdiff-backup-data# rdiff-backup 
> --check-destination-dir /backup/data/aulis
> --clip--
>
> Depending on your version of rdiff-backup and the exact situation, you might
> get an error like this:
>
> --clip--
> Exception 'RPath instance has no attribute 'inc_compressed'' raised of class 
> 'exceptions.AttributeError':
>    File "/var/lib/python-support/python2.4/rdiff_backup/Main.py", line 295, in 
> error_check_Main
>      try: Main(arglist)
>    File "/var/lib/python-support/python2.4/rdiff_backup/Main.py", line 315, in 
> Main
>      take_action(rps)
>    File "/var/lib/python-support/python2.4/rdiff_backup/Main.py", line 273, in 
> take_action
>      elif action == "check-destination-dir": CheckDest(rps[0])
>    File "/var/lib/python-support/python2.4/rdiff_backup/Main.py", line 781, in 
> CheckDest
>      dest_rp.conn.regress.Regress(dest_rp)
>    File "/var/lib/python-support/python2.4/rdiff_backup/regress.py", line 69, 
> in Regress
>      regress_rbdir(manager)
>    File "/var/lib/python-support/python2.4/rdiff_backup/regress.py", line 124, 
> in regress_rbdir
>      if has_meta_diff and not has_meta_snap: recreate_meta(meta_manager)
>    File "/var/lib/python-support/python2.4/rdiff_backup/regress.py", line 145, 
> in recreate_meta
>      writer = metadata.MetadataFile(temprp, 'w', check_path = 0)
>    File "/var/lib/python-support/python2.4/rdiff_backup/metadata.py", line 378, 
> in __init__
>      if compress and not rp_base.isinccompressed():
>    File "/var/lib/python-support/python2.4/rdiff_backup/rpath.py", line 1087, 
> in isinccompressed
>      return self.inc_compressed
>
> Traceback (most recent call last):
>    File "/usr/bin/rdiff-backup", line 23, in ?
>      rdiff_backup.Main.error_check_Main(sys.argv[1:])
>    File "/var/lib/python-support/python2.4/rdiff_backup/Main.py", line 295, in 
> error_check_Main
>      try: Main(arglist)
>    File "/var/lib/python-support/python2.4/rdiff_backup/Main.py", line 315, in 
> Main
>      take_action(rps)
>    File "/var/lib/python-support/python2.4/rdiff_backup/Main.py", line 273, in 
> take_action
>      elif action == "check-destination-dir": CheckDest(rps[0])
>    File "/var/lib/python-support/python2.4/rdiff_backup/Main.py", line 781, in 
> CheckDest
>      dest_rp.conn.regress.Regress(dest_rp)
>    File "/var/lib/python-support/python2.4/rdiff_backup/regress.py", line 69, 
> in Regress
>      regress_rbdir(manager)
>    File "/var/lib/python-support/python2.4/rdiff_backup/regress.py", line 124, 
> in regress_rbdir
>      if has_meta_diff and not has_meta_snap: recreate_meta(meta_manager)
>    File "/var/lib/python-support/python2.4/rdiff_backup/regress.py", line 145, 
> in recreate_meta
>      writer = metadata.MetadataFile(temprp, 'w', check_path = 0)
>    File "/var/lib/python-support/python2.4/rdiff_backup/metadata.py", line 378, 
> in __init__
>      if compress and not rp_base.isinccompressed():
>    File "/var/lib/python-support/python2.4/rdiff_backup/rpath.py", line 1087, 
> in isinccompressed
>      return self.inc_compressed
> AttributeError: RPath instance has no attribute 'inc_compressed'
> --clip--
>
> You can solve it by editing
>
>    /var/lib/python-support/python2.4/rdiff_backup/metadata.py
>
> and changing line 378 to
>
>    if compress and rp_base.isincfile() and not rp_base.isinccompressed():
>
> and then running rdiff-backup --check-destination-dir again.
>
> After rdiff-backup returns, the backup should be regressed to the previous
> version (and have only one current_mirror file). You can repeat the process,
> one varsion at a time, for as many times as you wish. So if you want to regress
> two versions, just repeat the process once.
>
>
> --Janne

rdiff-backup-regress
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