Re: [Duplicity-talk] Differential/incremental backups

[Colin Ryan]

Rik,

I'll admit I've not run this fully yet only mocked up the scenario but 
I've been thinking of the same approach.

I sync to a backup folder from LAN to NAS target folder.
I run rsnapshot on the NAS target folder.
I then run duplicity on the daily.0 rsnapshot folder.

It seems to work as you seem to be hoping, and in my quick experiments 
the lack of handling of hard links by duplicity is actually beneficial here.

Rsnapshot runs and detects changed _files_ (verses blocks) and does it's 
rotations. The rotation directories will have the actual changed files 
in them and are filled in with hard links.

My quick experiments showed that running duplicity in incremental - ( 
and my understanding it is the type of incremental we want which is 
changes since the last backup not the last full backup ) - mode against 
the daily.0 the filled in files since they are inode references are not 
detected as changed (despite the rsnapshot rotation) , truly new files 
are detected and the only other thing that is noticed by duplicity is 
the timestamp on the daily.0 directory itself.

When I ran quickly through this rotations via rsnapshot where there was 
no changed files and this caused duplicity to ONLY detect the change to 
the directory timestamp and a modest 1-2 kb destination charge. Likewise 
when I new there truly was a changed file it would appropriately note 
this singular file change only and hence would only back up that single 
file.

So unless I've missed something obvious - i.e. what duplicities 
incrementals are - it seems to work like you would prefer so I'm curious 
about your statement of "

I end up with multiple "snapshots" on the offsite
server, as well. Which uses unnecessary disk space (I already have
snapshots locally).

"

Sorry it's not an answer but more a "me too" response.


Rik v. A wrote:
> Hi, I've been using Duplicity for a few months now, to create weekly
> backups from a backup NAS to an offsite backupserver. Machines in my
> network push their backups daily and weekly to a local NAS machine.
>
> Since storage space on an offsite server is expensive, storage
> capacity is obviously limited. That's why backups snapshots are
> created on the local NAS machine (using rsnapshot), because there's
> plenty of diskspace on that machine. That way, as long as my apartment
> doesn't burn down, I can always quickly recover a backup from a few
> days or weeks ago.
>
> This NAS copies the latest (daily) backup to the offsite backupserver,
> every weekend, using Duplicity. However, since Duplicity create
> incremental backups, I end up with multiple "snapshots" on the offsite
> server, as well. Which uses unnecessary disk space (I already have
> snapshots locally).
>
> I could solve this by creating a full backup regularly, however this
> defies the whole use of Duplicity; because our upload speed is very
> limited, and traffic is expensive, we are forced to use
> incremental/differential backups.
>
> What I _really_ want, is a full backup created once, and every time I
> run duplicity, it should update this backup, by only updating changed
> files.
>
> Kinda like "rsync --verbose --backup --archive --compress --force
> --ignore-errors --delete" (which is the line I use to create
> incremental backups from one server to the backup NAS), but with the
> encryption.
>
> According to Wikipedia
> (http://en.wikipedia.org/wiki/Incremental_backup), this is not
> incremental nor differential, so I wouldn't know what to call it.
>
> So after this long story, my question is: Is this possible with
> Duplicity, and if yes, how?
>
> Kind regards,
> Rik v. A
>
>
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