didier gaumet wrote: > > I may be mistaken, but I think there is a confusion here about a > deduplication at filesystem level and at backup tool level. > > At (linux) filesystem level, I think in-line deduplication is only provided > by ZFS (and perhaps, out-of-tree, BTRFS)
ZFS deduplication is a special beast that usually does not make people happy. It is an enterprise feature that really only works for special cases, and requires a lot of RAM - 1GB per 1TB of storage - to work. Worst of all, it cannot be gracefully turned off. As you say, deduplication in backup systems is quite common, and works pretty well. There's also an on-disk non-filesystem utility, rdfind, which is packaged in Debian. It can discover identical files and make them hardlinks. -dsr-