The GFS media pools are special media pools that store data to tape according to the GFS, or Grandfather-Father-Son rotation scheme. The GFS media pools are targets for GFS tape jobs. For details, see GFS Backup to Tape.
GFS media pool keeps four predefined media sets for storing the VM backups with a tiered retention policy scheme:
You can disable any media set or sets if you do not need them.
A GFS media pool can be target for unlimited number of GFS tape jobs.
You can target a tape job to a simple media pool or a GFS media pool, but not to both types simultaneously. A tape job targeted to a GFS media pool produces only full backups by the GFS schedule. Thus, GFS media pool cannot be used for incremental backup. If you want to have both GFS and simple retention backups for some VMs, create two tape jobs processing the same VM. Target one of these jobs to a GFS media pool and the other to a simple media pool.