It sounds like nobody actually understood what you want.

You have a non-ZFS boot drive, and a big ZFS pool, and you want to save an image of the boot drive to the pool, as a backup for the boot drive.

I guess you don’t want to image the drive while booted off it, because that could produce an image that isn’t fully self-consistent. So then the problem is getting at the pool from something other than the system you have.

I think what you need to do is find something else you can boot that supports ZFS. I think the Ubuntu live images will do it. If not, you can try something like re-installing the setup you have, but onto a USB drive.

Then you have to boot to that and zfs import your pool. ZFS is pretty smart so it should just auto-detect the pool structure and where it wants to be mounted, and you can mount it. Don’t do a ZFS feature upgrade on the pool though, or the other system might not understand it. It’s also possible your live kernel might not have a new enough ZFS to understand the features your pool uses, and you might need to find a newer one.

Then once the pool is mounted you should be able to dd your boot drive block device to a file on the pool.

If you can’t get this to work, you can try using a non-ZFS-speaking live Linux and dding your image to somewhere on the network big enough to hold it, which you may or may not have, and then booting the system and copying back from there to the pool.

I think you can keep doing the SMB shares and use an overlay filesystem on top of those to basically stack them on top of each other, so that server1/dir1/file1.txt and server2/dir1/file2.txt and server3/dir1/file3.txt all show up in the same folder. I’m not sure how happy that is when one of the servers just isn’t there though.

Other than that you probably need some kind of fancy FUSE application to fake a filesystem that works the way you want. Maybe some kind of FUES-over-Git-Annex system exists that could do it already?

I wouldn’t really recommend IPFS for this. It’s tough to get it to actually fetch the blocks promptly for files unless you manually convince it to connect to the machine that has them. It doesn’t really solve the shared-drive problem as far as I know (you’d have like several IPNS paths to juggle for the different libraries, and you’d have to have a way to update them when new files were added). Also it won’t do any encryption or privacy: anyone who has seen the same file that you have, and has the IPFS hash of it, will be able to convince you to distribute the file to them (whether you have a license to do so or not).

Why does Lemmy even ship its own image host? There are plenty of places to upload images you want to post that are already good at hosting images, arguably better than pictrs is for some applications. Running your own opens up whole categories of new problems like this that are inessential to running a federated link aggregator. People selfhost Lemmy and turn around and dump the images for “their” image host in S3 anyway.

We should all get out of the image hosting business unless we really want to be there.