I am looking for something like this instead of tape backups. I looked at some NAS devices that hold five drives and seem pretty robust. One of the devices can mirror itself to another NAS over the network so you can have two separate places to store your data and not have a hardware failure of one device kill the other.(one exception would be the case where the master device gets degraded to the point where bad data is being written to it and then propagates the changes to the other device. I don't know how likely this failure situation is though.)