I'm going to be setting up an 8x20TB ZFS RaidZ2 with no spare. This will give me roughly 100TB of storage for large 3D model files.
I want to purchase some extra HDDs so I can periodically backup and store this data off-site. While I could buy an extra 8x20TB and use dd to copy the drives, it would be nice if I could copy the data to 5x20TB drives instead.
I'd like to do this without building a separate computer to do so. I was thinking I could connect the backup drives over USB (slow is ok). Is there good software or a method I can use to copy across multiple disks? If it's possible, I would like to avoid a situation where I don't have enough total space across the backup drives due to file-by file copy leaving too much "slack" on each of the drives when a file is too big to fit but there's still usable space on the drive.
If this idea is totally moronic, I'm open to others, but I would like to avoid cloud providers yearly fees. I'm a one man shop, not a mega-corp.