Using RAID1 vs. rsync pros and cons

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http://serverfault.com – I am building myself a Linux NAS/home server. I am considering either using sw RAID-1 (mdadm) to replicate data or alternatively just rsync them periodically. What are advantages/disadvantages of both approaches. I am adding my assumption as an answer, but I'd like to make this list of pros/cons more comprehensive. (HowTos)