Since it was a lot of work to figure all this out i figured i'd let others know: So I have an assortment of machines on various OS'es now at home, macs, windows, linux. I needed a way to (ideally) back everything up the same way. Also, Apple's Time Machine, as easy as it is to use, was starting to piss me off, at least over a network (taking forever, causing the computer to lag terribly, often saying it had to rebuild the entire backup from scratch, that sort of thing... It always worked fine to a local disk, but I wanted reliable network backup) I decided early on to stick to using S3 protocol to a FreeNAS Mini I already own since pretty much all the backup software I was evaluating was able to speak S3, from all the OS'es. This would also make it easy to switch to actual cloud down the line if that made sense. S3 support provided by Minio http://www.min.io/ was recently added to my FreeNAS and it turns out, Minio is also easily installable on OS X (via Homebrew) and Linux, which meant that I could use my Mac Mini hooked up to a Drobo as a backup backup server (more on this soon) In parallel with all this I decided to upgrade the capacity of my FreeNAS disks to 10TB each, which entails replacing a drive, waiting 24+ hrs for a resilver, and repeating. I eval'd https://www.retrospect.com/, https://arqbackup.com/ and https://www.cloudberrylab.com/. Retrospect (which I know from a long time ago in my Mac OS 9 days) is the best product overall, but is also the most expensive, and doesn't have a Linux version. Great if you want great support, a great product, don't need Linux compatibility and have the cash though. Arq is great for Macs and Windows and speaks S3 (and has a separate Cloud product). It has toggleable compression (LZ4) and always encrypts (not toggleable yet). Then I discovered Cloudberry. Cloudberry looked great for everything but in testing I noticed it choked badly on some Mac filenames (since HFS+ is so permissive, characters like "" are permitted and that's exactly the one it choked on... I couldn't just rename them because these were files inside .app packages (!). So Cloudberry (for the time being) was out, at least for Macs (I reported the offending character to them, of course). But Cloudberry on Windows (not Mac, not sure if Linux) can do a full point-in-time system restore at the block level and could do block-level incremental (or differential) backups. I don't think anything else provided that except for maybe Apple's Time Machine. They promised a feature coming for Macs soon that did let you do this and took advantage of some snapshot/journaling features at the Mac filesystem level, but it wasn't out yet. I haven't gotten around to testing Cloudberry on Linux yet because while upgrading my FreeNAS, its boot volume died (!!!). My data is safe, but now that's another fiasco to deal with, so I've had to use my Mac Mini/Drobo combo in the interim. One nice thing Cloudberry can be configured to do is glacier-store your bulk data at Amazon S3, but incrementals are stored locally. That gets you performant backup plus total disaster recovery coverage (although restoration might take longer). Yet another reason to use S3 all around. So TL;DR: For in-house backup, S3 protocol still makes the most sense. For Macs, use Arq (or Time Machine, if you must, but it's flaky AF over a network). For Windows, use Cloudberry. For Linux, probably use Cloudberry, I'll update this after I get to testing it out.