Cluster Installation: Difference between revisions

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The following does ''not'' refer to the  [http://xds.mpimf-heidelberg.mpg.de/html_doc/xds_parameters.html#CLUSTER_NODES= CLUSTER_NODES=] setup. The latter does ''not'' require a queueing system!
The following does ''not'' refer to the  [http://xds.mpimf-heidelberg.mpg.de/html_doc/xds_parameters.html#CLUSTER_NODES= CLUSTER_NODES=] setup. The latter does ''not'' require a queueing system!


XDS can be run in a cluster using any command line job scheduling software such as Grid Engine, Condor, Torque/PBS, LSF, SLURM etc. These are distributed resource management system which monitor the CPU and memory usage of the available computing resources and schedule jobs to the least used computers.  
XDS can be run in a cluster using any batch job scheduling software such as Grid Engine, Condor, Torque/PBS, LSF, SLURM etc. These are distributed resource management system which monitor the CPU and memory usage of the available computing resources and schedule jobs to the least used computers.  


== setup of XDS for a batch queue system ==
== setup of XDS for a batch queue system ==


In order to setup XDS for a queuing system, the ''forkxds'' script needs to be changed to access the environment and send jobs to different machines, and to switch off the ssh-based mechanism which the CLUSTER_NODES keyword employs. Example scripts used for Univa Grid Engine (UGA) at Diamond (from https://github.com/DiamondLightSource/fast_dp/tree/master/etc/uge_array - thanks to Graeme Winter!) are below; they may need to be changed according to the environment. Observe this uses the ''qsub'' command which submits forkxds_job to grid engine.
In order to setup XDS for a queuing system, the ''forkxds'' script needs to be changed to use qsub instead of ssh. Example scripts used for Univa Grid Engine (UGA) at Diamond (from https://github.com/DiamondLightSource/fast_dp/tree/master/etc/uge_array - thanks to Graeme Winter!) are below; they may need to be changed for the specific environment and queueing system.  


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echo $SGE_TASK_ID | $JOB
echo $SGE_TASK_ID | $JOB
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== Performance ==
Cluster nodes may have different numbers of processors.
Please note that the output line
number of OpenMP threads used  NN
in COLSPOT.LP and INTEGRATE.LP may be incorrect if MAXIMUM_NUMBER_OF_JOBS > 1, and the submitting node (the node that runs xds_par) has a different number of processors than the processing node(s) (the nodes that run mcolspot_par and mintegrate_par). The actual numbers of threads on the processing nodes may be obtained by
grep PARALLEL COLSPOT.LP
grep USING INTEGRATE.LP | uniq
The algorithm that determines the number of threads used on a processing node is:
NB = DELPHI / OSCILLATION_RANGE  # this may be slightly adjusted by XDS if DATA_RANGE / NB is not integer
NCORE = number of processors in the processing node, obtained by OMP_GET_NUM_PROCS()
if MAXIMUM_NUMBER_OF_PROCESSORS is not specified in XDS.INP then MAXIMUM_NUMBER_OF_PROCESSORS = NCORE
number_of_threads = MIN( NB, NCORE, MAXIMUM_NUMBER_OF_PROCESSORS, 99 )
This is implemented in BUILT=20191015 onwards.
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