I am looking for some sort of clustered /dev/shm like device or RAM based, clustered filesystem, running on Linux, so it supports mirroring. Or there is anything stable enough which would do the job the same way? So I can replicate RAM based data? I would like to have it self-repairing (e.g. just restart recovers the service).
You could theoretically run drbd with the underlying devices being files on a tmpfs filesystem. Whatever you're doing sounds a bit crazy though...