SANs aren't filesystems. They're block devices that run over the network instead of over a SCSI cable. They connect to servers by special HBA cards which look like SCSI devices, but actually run the SCSI protocol over the network to a rack full of disks. In a SAN configuration, the admins of those disks carve out a volume of storage for you, give it a name, and you configure it on your server; now it looks like you have a couple terabytes of storage directly connected. You format it like any other disk.

Backup works like any other system; you do it app layer. In high-volume high-sensitivity apps, the people running the disk server also back it up, by running protocols that mirror block-level changes to a second rack full of disks somewhere in Tennessee.

(yes, yes, or IDE or FC, yes yes, or software initiator, etc etc).