Backing up SQL Large SQL DB with multiple data files

@Rupa 

There are a lot of factors that come into play for backup perforamnce. A thousand different hardware configs, network, media agent, backup disk target performance, SAN, etc

There is no one perfect setting. In general, assuming this is regular streaming backups you can certainly increase the streams from the default 2 to 6 or 8. Once that is set review performance in all aspects, clients, MA, etc Then you can adjust based on those results.

To directly answer the questions:

1. We are considering to increase the backup streams , the question is how many streams should be added ? Is it based on the size AND if the DB has multiple files? 1 stream per data file ?

1. when streaming via VDI its stream per database regardless of number of DB files.

1. Number of streams for DB with single file

1. see above, backup starts one database at a time and splits that up into number of streams set on config.