I take a nightly backup from my Webhosting service as .tar.gz. The Data changed is very little each night (<10MB).
I would like to archive these files and deduplicate (solid compression) files across multiple .tar.gz archives without extracting each individual backup file.
I want to compress and archive
2013-02-25.tar.gz and store
a.pdf only one time.
The only way I got the deduplication working was to unpack both .tar.gz and pack them again (using solid compression). But this is one additional step and it will probably erase filesystem information due to different OS's. Simply tar/gz both .tar.gz files won't work, the final size of this archive will be the sum of both original .tar.gz files.
Is there a way use deduplication across the contents of multiple .tar.gz files?