Re: [Duplicity-talk] --no-compression is broken WAS: Backup not restorable with no compression?

[edgar . soldin]

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
>         >>>>
>         >>>> _______________________________________________
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