You might want to reconsider the brand of RAM, Kingston has a bad reputation in these forums.
6TB data need to backup to the above machine.
Hope to have a solution to secure the data.
If your FreeNAS is a backup destination for other systems, and holds no data that's
both important
and irreplaceable, then you don't necessarily need a further backup.
I think your solution is good: RAIDZ2 + snapshot replication.
Do you understand that snapshots allow access to earlier versions of datasets, whereas replication is a way of transferring a snapshot to another system (or to another pool on the same system)? In other words, snapshots can be useful without replication.
