Introduction

SCore supports the following features:

• Single System Image
  Using SCore, users are not aware whether or not a system is a cluster of single/multi-processor computers or a cluster of clusters. A parallel application and an ordinary UNIX command may run by just specifying a computer node group of such a cluster. A Unix command runs in the SIMD execution style.

• Multiple Network Support
  The PM II high performance communication library is a dedicated communication library for cluster computing using many types of networks. PM II allows a program to communicate on different types of networks. PM II drivers for Myrinet, Ethernet, UDP, and the Shmem shared memory interface have been implemented.

• Seamless Programming Environment
  The Hmake command enables users to compile a program on heterogeneous computers. It generates binaries for different underlying types of execution environments such as Intel Pentium and Compaq processors. Using the MPC++ Multi-Threaded Template Library, a program runs on such a heterogeneous processor environment.

• Heterogeneous Programming Language
  Programs written in the MPC++ Multi-Threaded Template Library (MTTL) may not only run on homogeneous computer environment but also run on heterogeneous computer environment without modifying the code.

• Multiple Programming Paradigms
  Unlike other cluster software, SCore not only supports the message passing paradigm, but also supports the shared memory parallel programming paradigm and the multi-threaded parallel programming paradigm.

• Parallel Programming Support
  
  • Real-time process activity monitor
    SCore-D allows us to watch parallel process activity in real-time using the Real-Time Load Monitor. Each bar of the Real-Time Load Monitor represents the processor utilization on each node.

  • Deadlock detection
    Since SCore-D knows the global status of a parallel process, i.e., each process status and communication buffer status, it can detect whether or not the parallel process is deadlocked.

  • Automatic debugger attachment
    In most cluster systems, when a process dies, there is no chance to invoke a debugger interactively. SCore attaches the gdb(1) debugger to the target parallel process when an exception signal is detected.

• Fault Tolerance
  
  • Preemptive checkpoint
    To enable a checkpoint function, the SCore checkpoint facility does not require any additional API and does not assume any parallel programming languages. The user parallel process image is stored to a local hard disk for checkpoint by a user specified interval.

  • Parallel process migration
    Using the checkpoint function, a parallel process may migrate to another group of computers in SCore.

• Flexible Job Scheduling
  To utilize processor resources and to enable an interactive programming environment, the SCore-D global operating system multiplexes parallel processes in processors' space and time domains simultaneously.
  • Gang scheduling
    Parallel processes are gang-scheduled when multiplexed in the time domain.

  • Batch scheduling
    Batch scheduling is implemented by setting an infinite value for the scheduling slice time.