The HECToR Service is now closed and has been superceded by ARCHER.


This Distributed Computational Science and Engineering (dCSE) project was to evaluate the performance of the Ocean modelling code NEMO, improve IO and investigate the use of nested models.

The main achievements of the project are summarised below:

  • Compiled, tested and evaluated the performance of 2 versions of NEMO (2.3 and 3.0)
  • Achieved a reduction of up to 25% AU usage by removing land only cells from the computations.
  • Obtained an optimal processor count for a 12 hour run
  • Investigated how the grid dimensions affect the performance and concluded that square grids or those with jpin < jpnj are optimal
  • Compiled, tested and investigated the performance of netCDF 4.0, HDF5 1.8.1, zlib 1.2.3 and szip
  • Obtained a 3 fold reduction in disk usage and 4 fold reduction in runtime with the NOCSCOMBINE tool compiled with netCDF 4.0
  • Adapted NEMO to use netCDF 4.0 for its main output files, resulting in a reduction in disk usage of up to 3.55 times.
  • Investigated two different nested models BASIC & MERGED
  • Resolved the issues with the BASIC model and investigated the performance - 32 processors gives the optimal performance
  • Compiled the MERGED model and identified various problems with the velocity becomming too large
  • Compiler and debugger issues identified and under investigation
  • Presentations given at the HECToR User Group (September 2008) and HPCx Parallel I/O Workshop (December 2008)
  • Article for EPCC News
  • Contributed towards Scientific Computing World Article

Please see PDF or HTML for a report which summarises this project.