Larchant-RDOSS is a distributed shared memory that persists on reliable storage across process lifetimes. Memory management is automatic: caching of data and of locks, coherence, collecting objects unreachable from the persistent root, writing reachable objects to disk, and reducing store fragmentation. Memory management is based on a novel garbage collection algorithm, that (i) approximates a global trace by a series of partial traces within dynamically determined subsets of the memory, (ii) causes no extra I/O or locking traffic, and (iii) needs no extra synchronization between the collector and the application processes. This results in a simple programming model, and expected minimal added application latency. The algorithm is designed for the most unfavorable environment (uncontrolled programming language, reference by pointers, non-coherent shared memory) and should work well also in more favorable settings.