There was a practice of using MergerFS/OverlayFS for pooling multiple drives (often by SnapRAID users), but what's still missing (to my knowledge) is some sort of a balancing layer, that could distribute writes.
I got this idea many years ago, when first personal cloud storages appeared and offered some limited space for free. I thought it would be nice if I could pool them and fill them taking their different capacities into account. And if I could also stripe and EC them for higher availability...
I still wonder if there's something that can do this and if there isn't I would like to know why, since it looks like a useful and obvious idea.
What do you mean by "distribute writes"? One of mergerfs' primary features has always been it's policies which provide different algorithms for choosing a branch to apply a particular function to.
aufs sort of could do that at the file layer. The issue is you run into a bunch of incompatibilities with how applications can expect it to work. As soon as you want to start looking at striping and EC then you really need to just go with something like ZFS or btrfs.
I got this idea many years ago, when first personal cloud storages appeared and offered some limited space for free. I thought it would be nice if I could pool them and fill them taking their different capacities into account. And if I could also stripe and EC them for higher availability...
I still wonder if there's something that can do this and if there isn't I would like to know why, since it looks like a useful and obvious idea.