Why did I write the application ? When I read about Apple’s TimeMachine I thought it’s nice tool to have. I searched for equivalent applications for Linux and I find TimeValut and FlyBack. I didn’t feel very comfortable with TimeVault, especialy with it’s timeline. FlyBack was almost what I was looking for: I wanted a Places/Bookmarks column and I wanted snapshots only when something changed (just to reduce the number of snapshots).
Keep in mind that Back In Time is just a GUI. The real magic is done by rsync (take snapshots and restore), diff (check if somethind changed) and cp (make hardlinks).
Back In Time acts as a “user mode” backup system. This means that you can backup/restore only folders you have write access to (actually you can backup read-only folders, but you can’t restore them).
If you want to run it as root you need to use “su” (command line), “gksu” (Gnome) or “kdesudo” (KDE).
A new snapshot is created only if something changed since the last snapshot (if any).
A snapshot contains all the files from the selected directories (except for exclude patterns). In order to reduce disk space it use hard-links (if possible) between snapshots for unchanged files. This way a file of 10Mb, unchanged for 10 snapshots, will use only 10Mb on the disk.
When you restore a file ‘A’, if it already exists on the file system it will be renamed to ‘A.backup.<current data>’.
For automatic backup it use “cron” so there is no need for a daemon, but “cron” must be running.
Starting from version 0.9.24 permissions and user/group are stored in a special file. This way you can even save/restore files from a NTFS/FAT drive without losing this informations (NOTE: FAT don’t support hard-links).