"Num Volumes" doesn't match what is expected

answers inline

On 27.07.2017 21:03, baldwintm wrote:
> New question #653959 on Duplicity:
> https://answers.launchpad.net/duplicity/+question/653959
>
> I am running backups using duply.
> I have "VOLSIZE = 250" in the duply conf file, backing up a directory with 3.6 TB of data.
> In the output of "duplicity collection-status", I have the following backup chains:
>
>
> Collection Status
> -----------------
> Connecting with backend: LocalBackend
> Archive dir: <REDACTED>
>
> Found 2 secondary backup chains.
> Secondary chain 1 of 2:
> -------------------------
> Chain start time: Sun Jun 11 00:32:04 2017
> Chain end time: Sun Jun 18 00:32:04 2017
> Number of contained backup sets: 4
> Total number of contained volumes: 8792
> Type of backup set: Time: Num volumes:
> Full Sun Jun 11 00:32:04 2017 6032
> Incremental Thu Jun 15 00:32:03 2017 2543
> Incremental Sat Jun 17 00:32:04 2017 153
> Incremental Sun Jun 18 00:32:04 2017 64
> -------------------------
>
> Secondary chain 2 of 2:
> -------------------------
> Chain start time: Mon Jun 19 00:32:03 2017
> Chain end time: Sun Jun 25 00:32:05 2017
> Number of contained backup sets: 3
> Total number of contained volumes: 8669
> Type of backup set: Time: Num volumes:
> Full Mon Jun 19 00:32:03 2017 5582
> Incremental Fri Jun 23 00:32:04 2017 2808
> Incremental Sun Jun 25 00:32:05 2017 279
> -------------------------
>
>
> Found primary backup chain with matching signature chain:
> -------------------------
> Chain start time: Mon Jun 26 00:32:05 2017
> Chain end time: Thu Jul 27 00:32:05 2017
> Number of contained backup sets: 26
> Total number of contained volumes: 11512
> Type of backup set: Time: Num volumes:
> Full Mon Jun 26 00:32:05 2017 1633
> Incremental Wed Jun 28 00:32:30 2017 1821
> Incremental Fri Jun 30 00:32:05 2017 4707
> Incremental Tue Jul 4 00:32:04 2017 534
> Incremental Wed Jul 5 00:32:04 2017 109
> Incremental Thu Jul 6 00:32:04 2017 116
> Incremental Fri Jul 7 00:32:04 2017 150
> Incremental Sat Jul 8 00:32:06 2017 122
> Incremental Sun Jul 9 00:32:04 2017 103
> Incremental Mon Jul 10 00:32:04 2017 118
> Incremental Tue Jul 11 00:32:04 2017 446
> Incremental Wed Jul 12 00:32:05 2017 76
> Incremental Thu Jul 13 00:32:04 2017 79
> Incremental Fri Jul 14 00:32:05 2017 78
> Incremental Sat Jul 15 00:32:03 2017 80
> Incremental Sun Jul 16 00:32:05 2017 70
> Incremental Mon Jul 17 00:32:04 2017 83
> Incremental Tue Jul 18 00:32:04 2017 392
> Incremental Thu Jul 20 00:32:03 2017 119
> Incremental Fri Jul 21 00:32:03 2017 92
> Incremental Sat Jul 22 00:32:04 2017 86
> Incremental Sun Jul 23 00:32:04 2017 77
> Incremental Mon Jul 24 00:32:04 2017 80
> Incremental Tue Jul 25 00:32:04 2017 97
> Incremental Wed Jul 26 00:32:06 2017 120
> Incremental Thu Jul 27 00:32:05 2017 124
> -------------------------
> No orphaned or incomplete backup sets found.
> --- Finished state OK at 14:15:08.826 - Runtime 00:00:12.894 ---
>
>
> So I would expect that I can take the value under "num volumes" for the full backups and divide them by 250 to get a number close to 3600, but I don't.

correct

> 1) why is this number so far off from what I expect?

compression? for the current primary chain i have no explanation though. it should have roughly the same amount volumes as the previous two provided that the data size was similar and big files didn't become better compressible somehow.

> 2) how can I tell the volume of data that is in each backup set? (which is my ultimate goal)
>

this functionality in not provided by duplicity so far. you could consider disabling compression (--gpg-options or --no-compression) but that of course would need more place on your backup disks, i see that you are doing backup locally.

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