HP D2D100 Backup System - Manual (Page 21)

Compression
The HP D2D Backup System does not apply hardware compression to backed-up data, but if you are
moving data from the HP D2D to physical tape, bear in mind that HP StorageWorks tape drives do apply
compression. Therefore, 200 GB of data on the HP D2D Backup System will require less space on a
physical tape cartridge. If moving data to a physical cartridge for offsite storage, there is no need for
concern if the data seems to utilize less space.
Some users may choose to enable software compression from their backup application to increase
the storage space available to the backup application, but this can make backup jobs slower to run.
However, once software compression has been applied, the data is not further compressed when it is
exported to a physical tape directly attached to the HP D2D Backup System. This ensures that the user
knows exactly how much physical cartridge space is required for export or copy.
D2D Backup System 21