zpaq is a journaling, incremental, deduplicating archiver.
"Journaling" means that when you update a file or directory, both the
old and new versions are saved and can be extracted. "Incremental"
means that only those files whose last-modified date has changed
since the previous backup are added. For 100 GB of files, this
typically takes 1-2 minutes, vs. a few hours to create the first
version. "Deduplicating" means that identical files or fragments are
stored only once to save time and space.
SUSE-Public-Domain AND MIT