[Guest]

While I use raid 1 (ilnux software raid is quite good); there was a recent research article which strongly suggest that 1 fault tolerance is very poor with regards for overall security. In your specific case you have 2 copies on raid 5 which is better. For folks that don't know ZFS advantage over ext4, fat32 or NTFS is that it provides checksum at the block level (i recommend you use sha-256). for the storage system I've worked on we support arbitrary d+p but generally use 2 copies @ 8+2 (raid5 is 2+1 but the parity is striped across all three disks). To be honest in my home systems I've only had 2 disk failures over the past 20 years and both disks were the same brand and died with in 2 years (worse they were corrupting data before failure - they were samsung f3 1tb drives). As other mention you really should keep an off site copy of the most important data (or have fireproof safe though I question that it can keep the drives/dvd cool enough in the event of serious fire). I don't keep a backup copies of pictures but I do keep a coupld of dvd @ relative house. I used to use tape (around 1998-2001 but gave up as drive density outpaced them. Hum. Wished zfs was better integrated into linux.

Got ZFS Raid Z (that's how level 5 is called with that file system) on one machine and it's automatically mirrored on regular basis over lan to another machine which also has ZFS (but not RAIDed). Both systems have unbuffered ECC memory, partitions are = 4 TB. Never ever had a problem with any of my files.