Multiplexing and Multistreaming

Multiplexing:
Multiplexing will allow backups of multiple client machines to send data to a single tape drive simultaneously. This is useful for low end client machines with slow throughput (such as over a slow network connection). Since these client machines cannot send data fast enough to keep the tape drive busy.
Multiplexing is the process of alternately sending (interleaving) data. In this case, alternately writing or interleaving multiple clients data to a single tape
When is it Useful:
Multiplexing is useful when your tape drive throughput is faster than the rate at which data can be extracted from the source

Multistreaming is a process that divides your backup jobs into multiple sub-jobs (streams) that run simultaneously and sends data to the destination media (tape device or file system device).
Multistreaming lets you use all of the available tape devices on the system by splitting your backup jobs into multiple jobs using all available tape devices. As a result, it will increase the overall backup throughput compared with the sequential method
When is it Useful:
Multistreaming is useful when performing large backup jobs, since it is more efficient to divide multiple jobs between multiple backup devices