As a cheap offsite destination for backup,(assuming you have multiple destinations) this looks quite compelling. Although I don't think ZFS is stable on the pi

As a cheap offsite destination for backup,(assuming you have multiple destinations) this looks quite compelling. Although I don't think ZFS is stable on the pi just yet[1], so perhaps 4 sata drives is overkill. I would be interested in a single sata/cm4 carrier board though. [1]citation needed, I've not really looked...