Re: [Duplicity-talk] --no-compression is broken WAS: Backup not restorab

On 18 February 2014 09:32, <address@hidden> wrote:

could you elaborate why? jsut interested. ..ede

On 18.02.2014 15:14, Michael Terry wrote:
> I am very interested in the continuation of no-encryption.
>
>

> On 18 February 2014 07:32, Kenneth Loafman <address@hidden <mailto:address@hidden>> wrote:
>
> I'm not convinced we should support no-encryption and no-compression.
>
> ...Ken
>
>
>

> On Sun, Feb 2, 2014 at 12:38 PM, <address@hidden <mailto:address@hidden>> wrote:
>
> i spent some time on debugging this. here is the result so far
>
> renaming the volumes works because they are actually gzipped. this is because we have two bugs
>
> 1. in duplicity.write_multivol() we always create GZIPFiles, around line 396

> http://bazaar.launchpad.net/~duplicity-team/duplicity/0.6-series/view/head:/bin/duplicity#L396 <http://bazaar.launchpad.net/%7Eduplicity-team/duplicity/0.6-series/view/head:/bin/duplicity#L396>

>
> 2. our tarfile implementation does not complain when it can't read the file properly, but seems to deliver zero entries instead. i didn't dig up where it should do that but expect somewhere in 'tarfile.py'.
>
> sure, we could easily remove the option. it seems to be not even documented in the man page.
> BUT i strongly feel we should keep and fix it as
> - it'll help others to understand our data format better and
> - maybe in the future will make it easier to implement an even better replacement data format.
>
> unfortunately my python isn't good enough to implement the PlainWriteFile. i assume one could reuse the code of GzipWriteFile here

> http://bazaar.launchpad.net/~duplicity-team/duplicity/0.6-series/view/head:/duplicity/gpg.py#L347 <http://bazaar.launchpad.net/%7Eduplicity-team/duplicity/0.6-series/view/head:/duplicity/gpg.py#L347>

> and write into a python file object instead.
>
> any hints? Ken, Mike?
>
> bug number 2. is not that serious, but leaves a stale taste, as a proper error would be expected.
>

> ..ede/duply.net <http://duply.net>

>
>
> On 27.01.2014 18:03, Knut Krause wrote:
> > OK, I'd have to dig into that. Maybe I will. Until then it would be at least
> > great if the option is disabled. This is just 1 minute work for the devs and
> > it would prevent duplicity from creating a backup it cannot restore any more.
> >
> > Knut
> >

> > Am Montag, 27. Januar 2014, 17:39:18 schrieb address@hidden <mailto:address@hidden>:

> >> good to know! maybe some warm heart comes around and does just that. the
> >> reason that no compression isn't fixed is simply - no one cares enough for
> >> this option, obviously.
> >>
> >> speaking of "you guys should". how about you dig in and supply a patch?
> >> python is not brain surgery ;)
> >>
> >> the lesson for you should be. don't trust, verify! while duplicity is quite
> >> robust, it still has nooks and corners. just now, 0.6.23 fixed a bug that
> >> resulted in data loss when a backup was resumed.
> >>
> >> all this can be easily circumvented by periodically verifying your backups.
> >>

> >> ..ede/duply.net <http://duply.net>

> >>
> >> On 27.01.2014 16:06, Knut Krause wrote:
> >>> Just for your information: renaming the *.difftar files to *.difftar.gz
> >>> seems to result in a working restore again.
> >>>
> >>> You guys should really either remove or FIX the --no-compression option
> >>> though. This is behaviour is not acceptable for backup software.
> >>>
> >>>
> >>> Knut
> >>>
> >>> Am Montag, 27. Januar 2014, 15:21:14 schrieb Knut Krause:
> >>>> Hi,
> >>>>
> >>>> I created a backup using --no-compression. The filenames are
> >>>> duplicity-inc.20140113T152430Z.to.20140123T112751Z.vol8.difftar
> >>>> without the .gz ending.
> >>>>
> >>>> file on the other hand says:
> >>>> duplicity-inc.20140113T152430Z.to.20140123T112751Z.vol9.difftar:
> >>>> gzip compressed data, last modified: Thu Jan 23 13:16:42 2014, max
> >>>> compression
> >>>>
> >>>> Now I found
> >>>> http://lists.gnu.org/archive/html/duplicity-talk/2013-03/msg00001.html
> >>>> and
> >>>> https://bugs.launchpad.net/duplicity/+bug/1029516
> >>>> which suggests that this option is buggy since 2012.
> >>>>
> >>>> Any suggestions how to fix this? Can I just rename the files to *.gz or
> >>>> will this break the signature stuff?
> >>>>
> >>>>
> >>>> Knut
> >>>>
> >>>> _______________________________________________
> >>>> Duplicity-talk mailing list

> >>>> address@hidden <mailto:address@hidden>

> >>>> https://lists.nongnu.org/mailman/listinfo/duplicity-talk
> >>>
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From:	Michael Terry
Subject:	Re: [Duplicity-talk] --no-compression is broken WAS: Backup not restorable with no compression?
Date:	Tue, 18 Feb 2014 09:42:38 -0500