This allow the programmer or administrator to concentrate on availability, sharing, and scalability. UnixWare NonStop Clusters builds on this base to provide a robust and scalable SSI clustering environment implemented as Underware. NSC provides a full SSI by making all operating system resources transparently usable cluster wide. SSI's tend to concentrate on one specific area e.g. filesystem, distributed shared memory, system management. By making all operating system resources, such as processes, files and devices, usable cluster wide in a transparent manner whilst maintaining UnixWare semantics, NSC allows standard UnixWare applications to run unmodified on the cluster.
Applications automatically benefit from the system's inherent scalability and resilience.
Since NSC's underware level SSI makes use of the cluster transparent, system management is achieved by trivial extensions to the core UnixWare system management facilities. System resilience can be administered by operations such as the ability to specify alternative routes to multiported disks. To make full use of NSC's facilities, additional API's are provided to allow applications to control placement and migration of processes, and to monitor and react to changes in the cluster's configuration. In order to provide a full SSI as underware, NSC supports all standard UnixWare API's and system calls. If a cluster operating system is to provide a full SSI, all operating system resources must be accessible clusterwide without needing to know where the resources are physically located.