Consider a read-only filesystem - or, better, part of a filesystem: a directory tree. How can I get redundancy for that without going to full RAID techniques (mirroring or otherwise)?
As an example of what I'm considering: WinRAR and Parchive are two archiving formats that allow for the creation of "recovery volumes" that provide redundancy for a set of identically sized files. They use standard RAID techniques (Reed-Solomon codes or something else suitable) to provide recovery against a certain number of lost or corrupted files: E.g., given a set of 10 large files you can create 2 recovery volumes to go with them such that any 10 of the 12 files will recover the full set. Or you can pick other levels of redundancy, 1 recovery file, 5, whatever.
So what I'd like is that - but without needing to put the directory tree into an archive! Is anything like that possible? (I.e., given a read-only directory tree I'd like to get one (or more) additional files that provide a certain level of redundancy against that directory tree at the cost of 10-30% disk space).
Acceptable solutions would include leveraging operating system features, e.g., userspace file systems, or something. (I'm specifically not interested in mere filesystem checksumming techniques that would allow me to detect corruption: It's recovery I want.)
I'm willing to be operating system agnostic and even filesystem agnostic - that is, if there is a technique that is OS- or filesystem- specific, I'd be willing to switch to it.