On Wed, Feb 06, 2008 at 02:03:04PM -0600, Les Mikesell wrote: > Robin Lee Powell wrote: > > >> > > This reminds me: is there some fundamental reason backuppc > >> > > can't use symlinks? It would make so many things like > >> > > this *so* much easier. It such a great package otherwise; > >> > > this is the only thing that's given me cause to be annoyed > >> > > with it. > >> > > >> > Still wondering this. > >> > >> with hard links, you can tell that a file in the main pool is > >> no longer needed, by looking at its link count. when the link > >> count goes to 1, none of the per-PC backup trees is referencing > >> it, so it can be deleted. (this is what the > >> BackupPC_trashClean process does.) > >> > >> with symlinks, you wouldn't get that reference count, and > >> "garbage collection" would be much more expensive. > > > > I'd happily pay the price in garbage collection to have > > something that could be remote mirrored easily. Judging by the > > number of requests this mailing list has had for such a feature, > > I'm not the only one. > > Hardlinking is an atomic operation, tied to the inode of the > filesystem so once established the target identity can't be > confused. Symlinks are just re-evaluated as filenames when you > open them.
Yes, I understand that. > So, if you created a symlink to a pooled filename, then the copy > in the pool directory is removed and re-created (likely, *Likely*? If that's likely, then backuppc need to change hash algorithms, because what you're describing requires a hash collision. Furthermore, keeping a list of what files point to what pool items shouldn't actually be that hard. > because you can't tell what symlinks need it), you'd end up with > filenames under the pc directory pointing to entirely wrong > contents. Again, that requires a hash collision. > > I'd even be willing to put some money forward if someone wants > > to code this feature; I'd rather not dig into backuppc's code if > > I can avoid it. > > This isn't really possible at the file level. I think the zfs > incremental send/receive might work. In some cases it might work > to just run a copy of backuppc remotely, saving directly to an > encrypted filesystem instead of trying to mirror a copy. Again: not being able to reasonbly mirror the backup system is a Real Problem; do you have other any ideas as to how to fix it? -Robin -- Lojban Reason #17: http://en.wikipedia.org/wiki/Buffalo_buffalo Proud Supporter of the Singularity Institute - http://singinst.org/ http://www.digitalkingdom.org/~rlpowell/ *** http://www.lojban.org/ ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ BackupPC-users mailing list BackupPC-users@lists.sourceforge.net List: https://lists.sourceforge.net/lists/listinfo/backuppc-users Wiki: http://backuppc.wiki.sourceforge.net Project: http://backuppc.sourceforge.net/
