CSAR Bulletin issued in October 2002

LSF: Load Sharing Facility

As you will be aware from previous CSAR Bulletins etc, the NQE batch system on green, fermat and wren will soon be replaced by LSF.

Green will be configured with 144 processors dedicated for LSF testing this week which allows three weeks of testing for users. We encourage users to try this out as soon as possible. This will reduce the number of processors dedicated for NQE jobs to 296.

Assuming no major problems are found, the "go-live" date for moving all of green, fermat and wren to LSF will be Wednesday 20th November 2002 (changes will be made during the planned maintenance of Tuesday 19th).

Please see link to LSF Userguide for further details of how to use LSF.

Please contact the CSAR Helpdesk should you have any queries regarding this.

Reducing Queuing Times: LSF or NQS

When you submit a job to an SMP machine (Green, Fermat, Wren or Fuji), you request a number of processors for a certain amount of time and also an amount of memory. The queue system then tries to fit your job with the other jobs running and queued, to find the best (soonest) time to run it. However, if you have asked for more resources than you need, you may find that one of two things happen:

1. the queue system will take longer to start your job even though there are some free processors/memory - because it needs to find a bigger space (time or RAM) to fit the job in; or
2. you get your job in, but other users' jobs are waiting longer than needed to run even though the computer has free processors/memory - because you have been allocated more than you actually need.

Please try to make sure that your qsub/bsub requests for cputime and memory are appropriate to what your job needs (use previous runs to make good estimates) - helping the queue system to use the computers more fairly for all users, including you.

If you require further information, please contact the CSAR Helpdesk

Software Update

Two new molecular dynamics packages - LAMMPS and NAMD - have been provided on the CSAR Origin systems. Please see link to CSAR software pages for further details.