Your NAS probably has a replication feature of some variety (although this may involve a license). If you want to stick with Symantec, look at Veritas Volume Replicator . There are a ton of vendors out there who have replication appliances as well, including probably whomever built your network switches. =)
You could use PureDisk with NetBackup Integration, so you will need 2 PureDisk environments (Storage Pool).
-The first Storage Pool needs to be integrated as Disk Storage Unit (PDDO)
-Then the first Storage Pool needs to be sync with to DR site (second Storage Pool)
-After that restore your applications as a normal restore.
NetBackup has an integration with DataDomain that it works a little simple (with deduplication).