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Single System Image

Single System Image. Infrastructure and Tools. PC/Workstation. PC/Workstation. PC/Workstation. PC/Workstation. Communications Software. Communications Software. Communications Software. Communications Software. Network Interface Hardware. Network Interface Hardware.

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Single System Image

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  1. Single System Image Infrastructure and Tools

  2. PC/Workstation PC/Workstation PC/Workstation PC/Workstation Communications Software Communications Software Communications Software Communications Software Network Interface Hardware Network Interface Hardware Network Interface Hardware Network Interface Hardware Cluster Computer Architecture Parallel Applications Parallel Applications Parallel Applications Sequential Applications Sequential Applications Sequential Applications Parallel Programming Environment Cluster Middleware (Single System Image and Availability Infrastructure) Cluster Interconnection Network/Switch

  3. A major issues in Cluster design • Enhanced Performance (performance @ low cost) • Enhanced Availability (failure management) • Single System Image (look-and-feel of one system) • Size Scalability (physical & application) • Fast Communication (networks & protocols) • Load Balancing (CPU, Net, Memory, Disk) • Security and Encryption (clusters of clusters) • Distributed Environment (Social issues) • Manageability (admin. And control) • Programmability (simple API if required) • Applicability (cluster-aware and non-aware app.)

  4. A typical Cluster Computing Environment Applications PVM / MPI/ RSH ??? Hardware/OS

  5. Applications PVM / MPI/ RSH Middleware or Underware Hardware/OS The missing link is provide by cluster middleware/underware PVM / MPI/ RSH

  6. Middleware Design Goals • Complete Transparency (Manageability): • Lets the see a single cluster system.. • Single entry point, ftp, telnet, software loading... • Scalable Performance: • Easy growth of cluster • no change of API & automatic load distribution. • Enhanced Availability: • Automatic Recovery from failures • Employ checkpointing & fault tolerant technologies • Handle consistency of data when replicated..

  7. What is Single System Image (SSI)? • SSI is the illusion, created by software or hardware, that presents a collection of computing resources as one, more whole resource. • SSI makes the cluster appear like a single machine to the user, to applications, and to the network.

  8. Benefits of SSI • Use of system resources transparent. • Transparent process migration and load balancing across nodes. • Improved reliability and higher availability. • Improved system response time and performance • Simplified system management. • Reduction in the risk of operator errors. • No need to be aware of the underlying system architecture to use these machines effectively.

  9. Desired SSI Services • Single Entry Point: • telnet cluster.my_institute.edu • telnet node1.cluster. institute.edu • Single File Hierarchy: /Proc, NFS, xFS, AFS, etc. • Single Control Point: Management GUI • Single virtual networking • Single memory space - Network RAM/DSM • Single Job Management: Glunix, Codine, LSF • Single GUI: Like workstation/PC windowing environment – it may be Web technology

  10. Availability Support Functions • Single I/O space: • Any node can access any peripheral or disk devices without the knowledge of physical location. • Single process Space: • Any process on any node create process with cluster wide process wide and they communicate through signal, pipes, etc, as if they are one a single node. • Checkpointing and process migration: • Can saves the process state and intermediate results in memory to disk to support rollback recovery when node fails. RMS Load balancing...

  11. Application and Subsystem Level Operating System Kernel Level Hardware Level SSI Levels • SSI levels of abstractions:

  12. Level Examples Boundary Importance Application batch system and system management An application What a user wants Distributed DB, OSF DME, Lotus Notes, MPI, PVM Sub-system A sub-system SSI for all applications of the sub-system Sun NFS, OSF, DFS, NetWare, and so on File system Shared portion of the file system Implicitly supports many applications and subsystems Toolkit OSF DCE, Sun ONC+, Apollo Domain Explicit toolkit facilities: user, service name, time Best level of support for heterogeneous system SSI at Application and Sub-system Levels (c) In search of clusters

  13. Level Examples Boundary Importance Kernel/ OS Layer Each name space: files, processes, pipes, devices, etc. Solaris MC, Unixware MOSIX, Sprite, Amoeba /GLunix Kernel support for applications, adm subsystems UNIX (Sun) vnode, Locus (IBM) vproc Type of kernel objects: files, processes, etc. Kernel interfaces Modularises SSI code within kernel None supporting OS kernel Virtual memory Each distributed virtual memory space May simplify implementation of kernel objects Mach, PARAS, Chorus, OSF/1AD, Amoeba Each service outside the microkernel Implicit SSI for all system services Microkernel SSI at OS Kernel Level (c) In search of clusters

  14. Level Examples Boundary Importance Application and Subsystem Level Operating System Kernel Level SCI, DASH memory memory space better communication and synchronization SCI, SMP techniques memory and I/O device space lower overhead cluster I/O SSI at Hardware Level memory and I/O (c) In search of clusters

  15. SSI Characteristics • Every SSI has a boundary. • Single system support can exist at different levels within a system, one able to be build on another.

  16. SSI Boundary SSI Boundaries Batch System (c) In search of clusters

  17. Relationship Among Middleware Modules

  18. SSI via OS path! • 1. Build as a layer on top of the existing OS • Benefits: makes the system quickly portable, tracks vendor software upgrades, and reduces development time. • i.e. new systems can be built quickly by mapping new services onto the functionality provided by the layer beneath. e.g.: Glunix. • 2. Build SSI at kernel level, True Cluster OS • Good, but Can’t leverage of OS improvements by vendor. • E.g. Unixware, Solaris-MC, and MOSIX.

  19. SSI Systems & Tools • OS level SSI: • SCO NSC UnixWare; • Solaris-MC; • MOSIX, …. • Middleware level SSI: • PVM, TreadMarks (DSM), Glunix, Condor, Codine, Nimrod, …. • Application level SSI: • PARMON, Parallel Oracle, ...

  20. UP or SMP node UP or SMP node Users, applications, and systems management Users, applications, and systems management Standard OS kernel calls Standard OS kernel calls Extensions Extensions Modular kernel extensions Modular kernel extensions Standard SCO UnixWarewith clustering hooks Standard SCO UnixWarewith clustering hooks Devices Devices ServerNet SCO Non-stop Cluster for UnixWare http://www.sco.com/products/clustering/ Other nodes

  21. How does NonStop Clusters Work? • Modular Extensions and Hooks to Provide: • Single Clusterwide Filesystem view; • Transparent Clusterwide device access; • Transparent swap space sharing; • Transparent Clusterwide IPC; • High Performance Internode Communications; • Transparent Clusterwide Processes, migration,etc.; • Node down cleanup and resource failover; • Transparent Clusterwide parallel TCP/IP networking; • Application Availability; • Clusterwide Membership and Cluster timesync; • Cluster System Administration; • Load Leveling.

  22. Sun Solaris MC • Solaris MC: A High Performance Operating System for Clusters • A distributed OS for a multicomputer, a cluster of computing nodes connected by a high-speed interconnect • Provide a single system image, making the cluster appear like a single machine to the user, to applications, and the the network • Built as a globalization layer on top of the existing Solaris kernel • Interesting features • extends existing Solaris OS • preserves the existing Solaris ABI/API compliance • provides support for high availability • uses C++, IDL, CORBA in the kernel • leverages spring technology

  23. Solaris-MC: Solaris for MultiComputers • global file system • globalized process management • globalized networking and I/O http://www.sun.com/research/solaris-mc/

  24. Solaris MC components • Object and communication support • High availability support • PXFS global distributed file system • Process management • Networking

  25. MOSIX: Multicomputer OS for UNIX http://www.mosix.cs.huji.ac.il/ || mosix.org • An OS module (layer) that provides the applications with the illusion of working on a single system. • Remote operations are performed like local operations. • Transparent to the application - user interface unchanged. Application PVM / MPI / RSH MOSIX Hardware/OS

  26. Main tool Preemptive process migration that can migrate  any process, anywhere, anytime • Supervised by distributed algorithms that respond on-line to global resource availability – transparently. • Load-balancing - migrate process from over-loaded to under-loaded nodes. • Memory ushering - migrate processes from a node that has exhausted its memory, to prevent paging/swapping.

  27. MOSIX for Linux at HUJI • A scalable cluster configuration: • 50 Pentium-II 300 MHz • 38 Pentium-Pro 200 MHz (some are SMPs) • 16 Pentium-II 400 MHz (some are SMPs) • Over 12 GB cluster-wide RAM • Connected by the Myrinet 2.56 G.b/s LANRuns Red-Hat 6.0, based on Kernel 2.2.7 • Upgrade: HW with Intel, SW with Linux • Download MOSIX: • http://www.mosix.cs.huji.ac.il/

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