Yes, of course, you must be right: the encryption process is a barrier to awareness between machines.
- dpb Developer and Lexicographer of Chinese brannerchinese.com On Thu, Sep 6, 2012 at 11:21 AM, Ryan DeShone <[email protected]> wrote: > On Wed 05 Sep 2012 03:33:59 PM EDT, David Prager Branner wrote: > > I'm new to Tarsnap as of last night and am very pleased with it. I > > have this question: > > > > I have some duplicate files on different machines, both backed up to > > the same Tarsnap account. It appears to me that in this situation, the > > usual economizing of space and archiving time — as when identical > > content is placed in the different archives on the *same* machine — is > > not taking place. Is that correct? Or is there something I can do to > > effect a savings here? > > > > Many thanks! > > From my understanding, deduplication takes place on the host, not the > server thus the data being backed up from two different hosts would not > be deduped against each other. Additionally, since all data is > encrypted in such a way that only the client is able to decrypt it, the > same raw data being backed up by two different hosts would be different > on the server (provided that you use different keys for each host, as > you should from a security standpoint). > > If you wanted to deduplicate backups from multiple hosts against each > other, you would need to copy the backups to a unified location, then > do one unified tarsnap backup of all the data from that centralized > location. This shouldn't be hard to do using rsync (provided your > machines are in the same physical location or at least have a decent > amount of bandwidth between them). > > Of course, this is all written based on my limited knowledge of the > internal workings of tarsnap, so I could be wrong. If so, someone feel > free to correct me :) >
