Data creation is possible and easy, especially in append only filesystems. Data updates can be done immutably by doing creates and rewriting the pointer structu

Data creation is possible and easy, especially in append only filesystems. Data updates can be done immutably by doing creates and rewriting the pointer structure, which obviously destroys cache fetch for highwater mark objects but doesn't affect cache marks for global id'd objects. Have you actually read the Paxos papers and the rest of the literature on this?