I mentioned yesterday that the approach used in BackupPC_copyPcPool to create an in-memory inode hash of the pool which I currently use to copy an entire BackupPC implementation can be extended to copy individual backups and thus in a sense perform incremental backups across two different BackupPC trees with different pool contents (and inode numbering).
This led me to think that one of the big current challenges with any notion of incremental backups is that pool chain renumbering creates a problem since there is no guarantee that a chain file has the same suffix after BackupPC_nightly runs. While I can get around this by creating a mapping between old and new pool file inode numbering (and naming), I realized that a small tweak to BackupPC_nightly would make such notions easier. If BackupPC_nightly instead of deleting files with one link, just zeroed them, then the space would be recaptured without any need for renumbering. In theory this would have only two small negative effects. First, you recover the space but you lose an inode. Second, chains will over time get longer slowing the resolution of md5sum pool name ambiguities when the whole chain needs to be walked (though zero size files should take minimal time to walk -- just a 'stat' really). Since chains are relatively rare, the cost may be worth bearing even though the solution is inelegant. But at least it would guarantee that the name and inode of a non-zero pool link would not change. Now I am not interested in going that direction because of it's inelegance, but it would solve some problems and open up some new pool syncing and backup solutions... ------------------------------------------------------------------------------ Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_feb _______________________________________________ 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/
