Re: [Duplicity-talk] command differences between duplicity and rsync !?

[Tim Riemenschneider]

SYNass IT Ubuntu / Linux schrieb:
> Hi Ryan 
>
> On Thu, 2008-06-19 at 12:24 -0700, Ryan Puckett wrote:
>   
> > duplicity --no-encryption /home/sna/ /media/LD149ext3/710e804
> >
> > Should do what you're asking for.
> >     
>
> Thanks for your feedback with my wished duplicity command !
>
> I have 2 more questions:
>
> 1) 
> Normally I use rsync with -av --delete --progress /...
> Does duplicity also use these or similars ?
>
>   
these options mean:
-v  extra verbosity: only for display purposes
--progress progress indicator: only for display
these two have no functional meaning, so they are hard to compare.... 
duplicity also has a -v switch for verbosity
-a     archive, same as -rlptgoD, they mean:
-r     recurse into subdirs, duplicity does that by default (unless you 
--exclude (some/all) subdirs
-l     copy symlinks as symlinks, duplicity does that also
-p    preserve permissions, duplicity does that
-t      preserve times, dito
-o,-g   preserve owner & groups, dito  (superuser only...)
-D    = --devices --specials     preserve device- and special files 
(fifos etc), duplicity does that, at least as root (I think?)

--delete   delete files not present in source dir, duplicity DOESN'T do 
this exactly, since it's against its purpose, only their deletion is 
recorded

duplicity and rsync serve some different purposes:
rsync synchronizes a directory to another host, so after it runs these 
paths are the same (it's some kind of a copy-operation)
duplicity saves the files as backup, so it's more like tar. Old files / 
the history of the files are recorded, so you don't only have the 
CURRENT state of these but (some) history of them. So you can not only 
restore the newest version of a file, but you can say "give me file xyz 
as it was 4 days ago".

so:
the first run of duplicity (or when you explicitly use the "full" 
command) does a full backup. This can be compared to a tar-backup. 
Additionaly it creates "signatures" of the files. These are equivalent 
to the checksums rsync creates/uses at runtime.
when you later use duplicity with the same source/target, it creates a 
backup consisting only of the differences to the previous backup: 
deleted files result in an internal remark "files xyz was deleted", new 
files are backed up as normal, for changes files it generates the 
difference using the signatures.

So depending an what you want to achieve, you should either use rsync 
(if you only want to synchronize the current state) OR duplicity (if you 
want to backup with history).
When using duplicity, you should either do explicit full backups from 
time to time, or use the option "--full-if-older-than TIME". Then you 
can use "remove-older-than" or "remove-all-but-n-full" to save space.
(I f.e. use "--full-if-older-than 7D" and "remove-all-but-n-full 4", to 
do weekly full-backups with daily (or even hourly...) incrementals, 
keeping aprox. one month of history (to limit space used on the 
backup-media). When I then need to restore a file that was deleted two 
weeks ago, I can use "restore -t 14D" to recover it)
> 2)
> I am still in an experimental phase to learn these kind of backup ! ;-)
> Can I use same targets for duplicity as for rsync as well or must /
> shall I 
> create and use 2 separate targets ??
>
>   
You should create 2 separate targets, since your rsync would delete the 
duplicity files (since you use "--delete")
> TIA for your advices and guidances.
> Cheers. svobi
>   
cu
Tim