These kinds of scenarios are why I built Relica [1]. It backs up to local disks, network drives, remote computers (on LAN or anywhere with a public IP address), your own cloud storage, or our own special formula we call the Relica Cloud: one upload, five independent cloud providers -- replicated in real-time.
And restores can use the open-source tool restic [2], so you don't have to be locked into Relica for accessing your data.
We're working on the ability to do byte-for-byte copies of a repository to other destinations to make data even harder to lose in these kinds of disaster scenarios, as well as a new UI to make it more pleasant and powerful.
Anyway, our goal is help make robust backup strategies like what this guy needs really, really painless, because I'm as paranoid as he should have been about losing data.
Can this also be used as a replacement for sync services such as Dropbox or SpiderOak ONE? In other words, can I sync accessible folders between computers in near-realtime, or is it only archival/backup storage?
No, Relica is not a sync service, because we do not want to sync your deletes -- we recommend using backup and sync together, because they serve two different functions.
Relica is archival software, but you can backup+archive your synced folders of course.
And restores can use the open-source tool restic [2], so you don't have to be locked into Relica for accessing your data.
We're working on the ability to do byte-for-byte copies of a repository to other destinations to make data even harder to lose in these kinds of disaster scenarios, as well as a new UI to make it more pleasant and powerful.
Anyway, our goal is help make robust backup strategies like what this guy needs really, really painless, because I'm as paranoid as he should have been about losing data.
[1]: https://relicabackup.com
[2]: https://github.com/restic/restic