Bontmia 0.14

Bontmia was written by John Enok Vollestad in april 2003 to merge the functionality of glastree and rsync in one application with a more flexible selection of long term storage. It has later gone through some changes to enhance usability
Main features:
Cost
- Tapes cost more than disks and require a tape-drive and possibly also a tape robot.
Reliability
- Disks have a higher MTBF than tapes and they require a tape drive of the same type. Disks can increase MTBF by being connected together to form RAID. Tapes can not. Incremental backup on a disk or a RAID volume does not change the MTBF while incremental backup on tape drastically lower the MTBF. Sometimes tapes written in one drive is difficult to read in another drive. This is a silent error if you do not test the tapes no and then. No such thing on file systems like ReiserFS.
Location
- Tapes is removable media and thereby avoiding the risk of localized disasters. A network connection does the same.
Time
- Copying just the changes gives a fast and efficient backup. Tape drives are very slow. Often slower than the network. Remote backup will therefore usually go faster to disk. Faster backup and efficient storage means one can do backup more often. Once every hour is usually not a problem. This also means rapid restore which is even more important.
Space
- Tapes split the data needlessly since they can not be used with RAID to form bigger volumes as disks can. Using hard-links on a file system gives very good storage efficiency and availability as ordinary file systems with random access.
- There is a lot of remote backup software out there. I wrote Bontmia since I could not find one that did all that I wanted.
Bontmia Functionality
- Each backup is a complete "snapshot" of the backed up directories.
- Files that is not changed since the last backup does not take up extra space and is not transferred over the network.
- Preserves a configurable selection of backups in a similar manner as tape rotation schemes.
- Remote backup is done encrypted over ssh for security reasons.
- Each backup is stored with absolute path.
- It is possible to limit the bandwidth to avoid affecting production systems.
- Support copying files, directories, device files, named pipes, symlinks and hard-links.
- Preserves user id, group id and permissions for all types of files.
Enhancements:
- Added support for specifying the directory for temporary files.