Distributed Shared Memory (DSM) is an interesting alternative to build distributed object system. Explicit message passing and remote invocation is replaced by the simple and unified DSM abstraction. The recurrent performance drawbacks of DSM Systems are often caused by expensive distributed locking mechanisms. In response to this our multipurpose Plurix Operating System (OS) implements a Transaction based DSM. Memory consistency is maintained by atomic transactions and optimistic synchronization mechanisms which have been used in database technology in the past. Such a transaction based DSM with optimistic synchronization guarantee a sequential consistent view on the shared data to every mode in the cluster.