I realize that I've posted some dumb things in this thread so here's a re-cast summary:
1) In the past, I experimented with fikesystem backups, using my own file-level checksumming that would detect when a file was already in the backup repository, and add a hard link rather than allocate new blocks. You can do that today on any [posix] fikesystem that supports hard links, by using rsync. But you are far, far better off using snapshots. 2) I said that I got 7-to-1 "deduplication" using my hard-link system. That's a meaningless statement, but anyway I was able to save twelve or so backups of a 100GB dataset on a 160GB hard disk. You would almost certainly see much better results by using snapshots on ZFS or btrfs, where a snapshot takes almost no storage to create, and only uses extra space for any changed blocks. Snapshots are block- level. 3) Another meaningless statement was my subjective notion that ZFS dedup led to performance degradation. Forget I said that, as actually I have no idea. My system was operating with failing drives at the time. Some people report better performace with ZFS dedup, as it decreases the number of disk writes. -- 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
