Hey list, I wonder if it is possible to deduplicate read-only snapshots.
Background: I'm using an bash/rsync script[1] to backup my whole system on a nightly basis to an attached USB3 drive into a scratch area, then take a snapshot of this area. I'd like to have these snapshots immutable, so they should be read-only. Since rsync won't discover moved files but instead place a new copy of that in the backup, I'm running the wonderful bedup application[2] to deduplicate my backup drive from time to time and it almost always gains back a good pile of gigabytes. The rest of storage space issues is taken care of by using rsync's inplace option (although this won't cover the case of files moved and changed between backup runs) and using compress-force=gzip. Since bedup sets the immutable attribute during touching the files, I suspect the process will no longer work when I make the snapshots read-only. I've read about ongoing work to integrate offline (and even online) deduplication into the kernel so that this process can be made atomic (and even block-based instead of file-based). This would - to my understandings - result in the immutable attribute no longer needed. So, given the fact above and for the case read-only snapshots cannot be used for this application currently, will these patches address the problem and read-only snapshots could be deduplicated? Or are read-only snapshots meant to be what the name suggests: Immutable, even for deduplication? Regards, Kai [1]: https://gist.github.com/kakra/5520370 [2]: https://github.com/g2p/bedup -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
