Definitely need some kind of replication/mirroring to occur between instances for DR, I was looking at how other decentralized systems for inspiration. Something like RAID where it's tolerant of one or two drive failures could be translated to Lemmy. When you set up a new instance it allows you to opt-in to a peer network where you host backup content from several other instances and your instance is backed up to several other (non-overlapping) instances.