Re: [Duplicity-talk] Duplicity doubt regarding incremental backups

[Cláudio Gil]

Hi,

I believe that, as you have configured:

1. The first time you run, duplicity makes a full backup.
2. The following times, it makes an incremental backup.
3. Nothing is ever deleted.

I think that remove-older-than considers all backups (full and incremental). Since each incremental backup depends on the previous backup, because you do not delete the last one nothing can be deleted. The last backup depends on the previous incremental, which is 2D older, which depends on the previous until you reach a full backup.

In the same way, since you specify remove-all-inc-of-but-n-full 1 and you only have 1 full backup, nothing gets deletes.

That's how duplicity works. Every time it is run it creates a backup, even if "empty". And that backup, unless asked otherwise, is incremental and depends on the previous. So you need to do a full backup eventually to be able to clean things up. The easiest way is to add --full-if-older-than <time> to the backup command.

To avoid doing a backup when things do not change you have to create a script around duplicity that possibly checks the output of a dry-run. Just note that while it seems cleaner to only have backups when things change, an incremental is very fast (my raspberry PI does an incremental backup of 500GB to S3 in under 15min, when nothing changes).

Cheers,
Cláudio

Em 21/02/2016 17:53, "NoPlanB" <address@hidden> escreveu:

Dear all,

I am using duplicity since a couple of days and it is working fine so far but I have one question regarding the incremental backups.
The backup will be initiated every day via cronjob as follows:

duplicity remove-older-than 1D --force $target
duplicity remove-all-inc-of-but-n-full 1 --force $target
duplicity cleanup --force $target
duplicity $source $target

As you can see I want to have only one backup without any incrementals.
My doubt is that every day when the cronjob is running it is placing an incremental backup to my FTP target even if the source has not been changed.
In general it is no problem but why duplicity is generating an incremental backup file if the source has not been changed?
It does not make sense for me because the target will be flooded with hundreds of files after a couple of months.
Furthermore why it is not possible to delete the older inc files? It says always to me that "....Which can't be deleted because newer sets depend on them".
Also here I cannot understand why there is a dependency if the source has not been changed.

Many thanks for your support!

Kind regards, Kai


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