Portsmouth ICG – HPC The “Sciama” Environment

G Burton - Nov 10 - Version 1.1

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SCIAMA (pronounced shama)

SEPNet Computing Infrastructure for Astrophysical Modeling and Analysis

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What we need from SEPNet partners:-

• Named “superuser”– Required for initial testing– Required for initial user training– Will require local IP range for firewall access

• Required software packages to be installed• Approximation of number of likely users

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Sciama Building Blocks

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In the “good-ol-days” things were simple ……….

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In the “good-ol-days” things were simple ……….

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… then more sockets were added

• Two main players are Intel and AMD• Single operating system controlling both sockets

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… then more cores to the sockets. The basic building block for the Sciama cluster

Intel Xeon X5650 2.66Ghz six-core (Westmere core)

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Total ICG Compute Pool > 1000 Cores

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Sciama Basic Concept

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Basic Concept of Cluster

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A bit about Storage ………

NB. The storage is transient - IT WILL NOT BE BACKED UP

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Lustre Storage – V Large Files – High Performance

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Networking -Three Independent LAN’S

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Some users are at remote locations ..

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Use of Remote Login Client

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ICG-HPC Stack

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Installed S/W

• Licensed Software:-– Intel Cluster Toolkit (compiler edition for Linux)– Intel Thread Checker – Intel Vtune Performance Analyser– IDL

• use ICG license pool ? • Restrict access ?)

– Matlab• use UoP floating licenses ?• Restrict access ? )

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Installed S/WWill install similar to Cosmos / Universe :-

• OpenMPI, OpenMP, MPICH• Opens source C, C++ and Fortran compiler suites• Maths Libs – ATLAS, BLAS, (Sca)LAPACK, FFTW

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Running Applications on the Sciama

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12 cores per Nodes

• Multiple cores allow for multi treaded applications.• OpenMP is an enabler

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Inter node memory sharing not (usually ) possible

• Gives rise to “distributed memory” Model• Need the likes of OpenMPI (Message Passing Interface)

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Largest (sensible) job is 24Gbytes in this distributed memory model

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MPI allows parallel programming in distributed memory model

• MPI enables parallel computation• Message Buffers are used to pass data between processes• Standard tcp-ip network used

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Hybrid OpenMP and MP programming possible

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Comparing Sciama with Cambridge COMOS / Universe Environments

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Shared Memory Model• Sciama is a distributed memory systems.• Cosmos – Universe environments are SGI Altix shared memory systems.

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Shared Memory Models Can Support very large processes

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Shared Memory Model Supports OpenMP and MPI (and Hybrid)

• Altix systems have an MPI Offload Engine for speeding upMPI comms.

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Binary Compatibility

• COSMOS and Universe are not binary compatible (Intel vs Itanium processors).

• Universe is compatible with Sciama but some libraries may be SGI Specific (MPI offload engine)

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