SSI Clusters
SSI Clusters
SSI Clusters
PC/Workstation
Communications Software
PC/Workstation
Communications Software
PC/Workstation
Communications Software
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.)
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Hardware/OS
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Hardware/OS
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Message Passing Interface (MPI) is an API specification that allows processes to communicate with one another by sending and receiving messages. It is typically used for parallel programs running on computer clusters and supercomputers, where the cost of accessing non-local memory is high. MPI is a language-independent communications protocol used to program parallel computers.
Scalable Performance:
Enhanced Availability:
SSI is the illusion, created by software or hardware, that presents a collection of computing resources as one, more whole resource.
In other words, it the property of a system that hides the heterogeneous and distributed nature of the available resources and presents them to users and applications as a single unified computing resource.
SSI makes the cluster appear like a single machine to the user, to applications, and to the network.
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SSI
Supported by a middleware layer that resides between the OS and user-level environment Middleware consists of essentially 2 sub-layers of SW infrastructure SSI infrastructure
Glue together OSs on all nodes to offer unified access to system resources Enable cluster services such as checkpointing, automatic failover, recovery from failure, & fault-tolerant support among all nodes of the cluster
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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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Single User Interface: using the cluster through a single GUI window and it should provide a look and feel of managing a single resources (e.g., PARMON). 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, SGE, LSF
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Any node can access any peripheral or disk devices without the knowledge of physical location. 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.
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
Hardware Level
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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
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Sub-system
A sub-system
SSI for all applications of the sub-system Implicitly supports many applications and subsystems Best level of support for heterogeneous system
File system
Toolkit
Operating System Kernel Level SCI (Scalable Coherent Interface), Stanford DASH
memory
memory space
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. Good, but Cant leverage of OS improvements by vendor. E.g. Unixware, Solaris-MC, and MOSIX.
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OS level:
SCO NSC UnixWare; Solaris-MC; MOSIX, . PVM/MPI, TreadMarks (DSM), Glunix, Condor, SGE, Nimrod, PBS, .., Aneka PARMON, Parallel Oracle, Google, ...
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Subsystem level:
Application level:
Extensions
Extensions
Devices ServerNet
Other nodes
Devices
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.
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 OS technology
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global file system globalized process management globalized networking and I/O
http://research.sun.com/techrep/1995/abstract-48.html
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Solaris MC components
Applications
Object and communication support High availability support PXFS global distributed file system Process management Networking
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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
Hardware/OS
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Supervised by distributed algorithms that respond online to global resource availability transparently. Load-balancing - migrate process from over-loaded to underloaded nodes. Memory ushering - migrate processes from a node that has exhausted its memory, to prevent paging/swapping.
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RMS system is responsible for distributing applications among cluster nodes. It enables the effective and efficient utilization of the resources available Software components
Resource manager
Locating and allocating computational resource, authentication, process creation and migration Queuing applications, resource location and assignment. It instructs resource manager what to do when (policy)
Resource scheduler
Provide an increased, and reliable, throughput of user applications on the systems Load balancing Utilizing spare CPU cycles Providing fault tolerant systems Manage access to powerful system, etc
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Resource Manager
execution results execution results
Computation Node 1
User 1
job
Job Manager
job
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Process Migration
Computational resource has become too heavily loaded Fault tolerant concern
Fault Tolerance Minimization of Impact on Users Load Balancing Multiple Application Queues
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http://www.pbsgridworks.com/
Hardware:
Offer the highest level of transparency, but it has rigid architecture not flexible while extending or enhancing the system. Offers full SSI, but expensive to develop and maintain due to limited market share. It cannot be developed partially, to benefit full functionality need to be developed, so it can be risky. E.g., Mosix and SolarisMC Easy to implement at benefit class of applications for which it is designed. E.g., Job management systems such as PBS and SGE. Easy to realise, but requires that each application developed as SSI-aware separately. E.g., Google
Operating System
Subsystem Level
Application Level
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Additional References
R. Buyya, T. Cortes, and H. Jin, Single System Image, International Journal of High-Performance Computing Applications (IJHPCA), Volume 15, No. 2, Summer 2001. G. Pfister, In Search of Clusters, Prentice Hall, USA. B. Walker, Open SSI Linux Cluster Project: http://openssi.org/ssi-intro.pdf
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