Data Domain - Usable Cartridge Capacity

Hi,

When you define the cartridge capacity on Data Domain side that corresponds to the pre-comp capacity. For instance a capacity of 100 GB for a tape.

When the Data Domain system will send an "End Of Media" notification to the backup server? After 100 GB have been sent by the backup server ? Or when 100 GB of physical data have been written on Data Domain side so much more from backup server view if you consider  ratio deduplication ?

Thanks for your help.

Alan