/tmp was mounted automatically as tmpfs in the /etc/fstab. It takes normally 1/2 Space of the RAM -> 1.6GB
duplicity first writes its cache of 2GB in the /tmp, which was to small -> not enough space left.
I uncommented the tmpfs-line in the /etc/fstab and now it works.
It works!
/tmp was mounted automatically as tmpfs in the /etc/fstab. It takes normally 1/2 Space of the RAM -> 1.6GB
duplicity first writes its cache of 2GB in the /tmp, which was to small -> not enough space left.
I uncommented the tmpfs-line in the /etc/fstab and now it works.
Sorry for the inconvenience.
Cheers