Duplication is always at the image level. If the source image is not multiplexed (which is always the case for images written on disk storage) it cannot be multiplexed at destination.
Hi,
You don't need to multiplex/demultiplex,remulitplex when you're going from Disk to Tape, and as Rasheed stated, Disk backups are never multiplexed. The reason being that tape is a sequential storage medium, while disk uses random access. This means disk can read and write anywhere on the disk. Where it actually reads from, and writes to, is controlled by the file system really.
Mulitplexing was designed so you can do multiple backups at the same time to the same tape. If this wasn't available, you'd need to wait for 1 backup to complete before running another. As you can imagine, this is not the case with disk, if you copy two files to the same disk, they are able to copy at the same time. In effect, the file system is multiplexing the files onto the disk (file system) for you. Therefore, netbackup doesn't need to worry about it.
So when talking about disk, from a netbackup point of view, the images are separate and not mushed up together as on tape. But on another layer, "underneath" the file system, or if you look at the blocks on the disk, it is mushed up.
Make sense?
