[Duplicity-talk] par2 backend produces empty .par files

[Pierre ROUDIER]

Hi,


I backup a folder using duplicity using the following command (please 
notice the use of the par2 backend).

duplicity --full-if-older-than 1M --name documents --no-compression 
--volsize 500 --encrypt-key XXXXXXXX --gpg-options "--compress-algo=none 
--cipher-algo=aes256 --digest-algo=sha512" --par2-redundancy 8 
--archive-dir /nfs/hubic_trantor/DuplicityArchiveDir 
/nfs/pierre_trantor/Documents/ par2+file:///nfs/hubic_trantor/Documents/


Problem : some .par files are empty (size is 0 bits). Therefore, it is 
impossible to use a par2 client to verify the recovery set.


Example with file 'duplicity-full.20150718T184613Z.vol1.difftar.gpg.par2'

address@hidden Documents.bak]$ ls -lh duplicity-full*.vol1.*
-rw------- 1 nobody nobody 501M Jul 18 20:47 
duplicity-full.20150718T184613Z.vol1.difftar.gpg
-rw------- 1 nobody nobody    0 Jul 18 20:47 
duplicity-full.20150718T184613Z.vol1.difftar.gpg.par2
-rw------- 1 nobody nobody  41M Jul 18 20:47 
duplicity-full.20150718T184613Z.vol1.difftar.gpg.vol000+160.par2


Calling par2cmdline manually, on the same file, gives the expected 
result (file duplicity-full.20150718T184613Z.vol1.difftar.gpg.par2 is 
not empty) :

-rw------- 1 pierre pierre 501M Jul 18 20:47 
duplicity-full.20150718T184613Z.vol1.difftar.gpg
-rw-r--r-- 1 pierre pierre  40K Aug  6 16:33 
duplicity-full.20150718T184613Z.vol1.difftar.gpg.par2
-rw-r--r-- 1 pierre pierre  41M Aug  6 16:33 
duplicity-full.20150718T184613Z.vol1.difftar.gpg.vol000+160.par2


The manual test was performed at the same location, in order to rule out 
any issue with the NFS.
The command line used was crafted looking at par2backend.py, in order to 
used the same parameters (got ride of -q -q):
par2 c -r8 -n1 duplicity-full.20150718T184613Z.vol1.difftar.gpg

I'm using duplicity version 0.7.03 and par2cmdline version 0.6.14 on 
ArchLinux x86_64


Am I doing something wrong? Has someone experienced something similar? 
(found nothing in the mailing archive) Any insight/clue would be greatly 
appreciated.


Thank you
Best regards
Pierre