Any

Lets NetBackup select the media owner, either a media server or server group.

None

Specifies that the media server that writes to the media that owns the media. No media server is specified explicitly, but you want a media server to own the media.

A server group

Specify a media server group to allow only those media servers in the group to write to the media on which backup images for this policy are written. All media server groups that are configured in the NetBackup environment appear in the drop-down list.