Best option to take backup which includes millions of files!

Dear All,

Good Day to All of you!

I have one query regarding the netbackup.My Master server is 7.6.0.1 on Solaris 10 Host.I have one Policy in  which the file systems conatins millions of files (20 Million) and total size is 700GB.So i want to know which is best option to take backup of this kind of file systems so that the backup should be faster now it is taking more than 12 hours.One friend was telling me about the Snapshot option but i dont know this and how it works.

Any Idea.

Thanks.

Regards,

Usman Salimi