[Borgbackup] question about deduplicated size stats

[Maurice Libes]

Le 12/09/2017 à 14:00, Thomas Waldmann a écrit :
>> why the size have changed ?
> Because the deduplicated size (== size of all chunks ONLY used by this 1
> archive) is relative to the state of the whole repository.
>
> So if you put these files into these archives (nothing else in that
> repo, A, B, C have no duplicate chunks):
>
> A     -> archive1
> A B   -> archive2
> A B C -> archive3
>
> After creating archive2, the new chunks from B will show up as unique
> chunks of archive2 (because they are not referenced by archive1).
>
> But after you create archive3, the chunks from B will be referenced
> twice (by archive2 and 3), thus they are not uniquely referenced by
> archive2 any more.
>
>
ok I have "almost" understood,

so the size returned by /*"borg info"*/ displays the stats of the 
deduplicated size (unique fragments)
  of one archive as compared to all the fragments in the whole repository ?
so it's a relative proportion of the unique fragments of one archive , 
which can evolve in the time when
new archives are added in the repository ?

After a great reflexion :-)  this is very confusing for my mind (and 
some friends) because we expected to find
the deduplicated size information as returned by the/*borg create*/ 
command at the time the backup was made

that is to say the deduplicated size of one archive at the time it is made
which is to my opinion more interesting to see the benefit of deduplication

exemple
time of "/_borg create_/" (extracted from log file)

Archive name: bioinfo-2017-09-07/** Original size Compressed size Deduplicated size This archive: 6.44 TB 
4.02 TB *2.44 GB* All archives: 65.05 TB 41.60 TB 3.96 TB**/


time of "_/borg info/_" some weeks later

Name: bioinfo-2017-09-07
                        Original size      Compressed size    Deduplicated size

This archive:                6.44 TB              4.02 TB/*110.13 MB*/
All archives:               66.26 TB             41.89 TB              4.29 TB


some weeks later we lose this information which shows that the day of 
the archive (09-07),
  borg added 2.44Gb of new fragments in the repository


we only know that in the 09-07 archive there are 110.13 Mb of unique 
fragments from this archive in the whole repository

dont know if i am clear (difficult to conceptualize and translate in 
english)

your opinion ?

ML


-- 
M. LIBES
Service Informatique OSU Pytheas - UMS 3470 CNRS
Batiment Oceanomed
Campus de Luminy
13288 Marseille cedex 9
Tel: 04860 90529

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