I would like to have a network filesystem (and/or synchronization setup) that behaves roughly like RAID 1 mirroring works for hard drives:
- Copies of every file are kept on every host, so that if you disconnect a single host from all the others it seamlessly continues using the latest versions of the files it’s seen.
- Upon reconnection, any changes to files can be automatically reconciled across all hosts as long as the file in question was only changed on a single host. (If the same file is changed in more than one place, it’s fine if this results in that part of the filesystem being regarded as corrupted, as long as this doesn’t affect unrelated files)
This has basically no performance requirements, but needs not to introduce any new behaviors into existing programs that work well when reading from disk. (For instance, no having a read or write block for a long time while waiting for the network to reconnect; no having a read result in an error when the file is present; etc.)
