Single System Image

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Single System Image

• Infrastructure and Tools

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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
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A major issues in Cluster design

• Enhanced Performance (performance _at_ 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.)

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A typical Cluster Computing Environment
Applications
PVM / MPI/ RSH
???
Hardware/OS
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The missing link is provide by cluster
middleware/underware
PVM / MPI/ RSH
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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..

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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.

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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.

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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

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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...

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SSI Levels

• SSI levels of abstractions

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SSI at Application and Sub-system Levels
(c) In search of clusters
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SSI at OS Kernel Level
(c) In search of clusters
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SSI at Hardware Level
memory and I/O
(c) In search of clusters
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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.

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SSI Boundaries
Batch System
(c) In search of clusters
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Relationship Among Middleware Modules
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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 Cant leverage of OS improvements by
  vendor.
• E.g. Unixware, Solaris-MC, and MOSIX.

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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, ...

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SCO Non-stop Cluster for UnixWare
http//www.sco.com/products/clustering/
Other nodes
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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.

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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

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Solaris-MC Solaris for MultiComputers

• global file system
• globalized process management
• globalized networking and I/O

http//www.sun.com/research/solaris-mc/
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Solaris MC components

• Object and communication support
• High availability support
• PXFS global distributed file system
• Process management
• Networking

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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
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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.

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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/