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- Users should request the lowest possible walltime for their jobs, since the queue system will need to "block out" the entire 24-hour period when no walltime is specified. This is analogous to a customer arriving at a busy barbershop and explaining that he only needs a "very quick trim."
- If users do not specify a queue in their script, the "default" queue is used. This queue has a walltime limit of 24 hours, a node count limit of 1, and a default priority of 60; in other words, it is less desirable than any of the queues listed in the tables below. Specifying a queue with the "#PBS -q" option is a good idea.
- Short "analysis scripts" are not exempt from the queuing system. If your script runs anything other than Linux utilities (e.g. VMD, CHARMM, custom C code for MD analysis), it belongs in the queue system. Just add a few lines as discussed in the section above.
- Input and output to files do not seem to be as immediate as when running directly from the command line. Users should not count on immediate access to program output.
- Users should test system scaling before expanding beyond one node; for systems of 10 to 20 katoms, poor scaling has been observed beyond 8 ppn, while the 92 katom ApoA1 benchmark case scales well to 2 nodes (and possibly beyond).
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