Warning: This document is for the development version of Bareos Documentation.

File Deduplication using Base Jobs

A base job is sort of like a Full save except that you will want the FileSet to contain only files that are unlikely to change in the future (i.e. a snapshot of most of your system after installing it). After the base job has been run, when you are doing a Full save, you specify one or more Base jobs to be used. All files that have been backed up in the Base job/jobs but not modified will then be excluded from the backup. During a restore, the Base jobs will be automatically pulled in where necessary.

Imagine having 100 nearly identical Windows or Linux machine containing the OS and user files. Now for the OS part, a Base job will be backed up once, and rather than making 100 copies of the OS, there will be only one. If one or more of the systems have some files updated, no problem, they will be automatically backed up.

A new Job directive Base=JobX,JobY,… permits to specify the list of files that will be used during Full backup as base.

Job {
   Name = BackupLinux
   Level= Base
   ...
}

Job {
   Name = BackupZog4
   Base = BackupZog4, BackupLinux
   Accurate = yes
   ...
}

In this example, the job BackupZog4 will use the most recent version of all files contained in BackupZog4 and BackupLinux jobs. Base jobs should have run with Level=Base to be used.

By default, Bareos will compare permissions bits, user and group fields, modification time, size and the checksum of the file to choose between the current backup and the BaseJob file list. You can change this behavior with the BaseJob FileSet option. This option works like the Verify, that is described in the FileSet chapter.

FileSet {
  Name = Full
  Include = {
    Options {
       BaseJob  = pmugcs5
       Accurate = mcs
       Verify   = pin5
    }
    File = /
  }
}

Warning

The current implementation doesn’t permit to scan volume with bscan. The result wouldn’t permit to restore files easily.