Difference: SystemAdministratorGuideForEMI1 (56 vs. 57)

Revision 572011-11-11 - MassimoSgaravatto

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META TOPICPARENT name="SystemAdministratorDocumentation"

System Administrator Guide for CREAM for EMI-1 release

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0.0.0.1 Tune the number of concurrent BLAH instances

To allow a parallelism when interacting with the batch system, in particular to have a good throughput when submitting jobs to the batch system, CREAM can run multiple BLAH instances. A new instance is created whenever needed, till the maximum number defined in the etc/glite-ce-cream/cream-config.xml configuration file is reached. The relevant attribute is cream_concurrency_level. The default value is 50.

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This value should be usually fine. You might need to decrease it if you notice an overload of the batch system and many jobs aborted because the submission to the batch system failed with "send command timeout" error message.

Please note that with BLAH version < 1.16.3, there are some memory issues: each BLAH instance uses too much memory and therefore a high value of this parameter can cause memory problems. The problem is fixed with BLAH version 1.16.3. Besides this version of BLAH, it is also needed to have in blah.config:

job_registry_use_mmap=yes

which is automatically added by yaim (starting with yaim-cream-ce version >= 4.2.2-1).

Starting with yaim-cream-ce version >= 4.2.3-1, this value for the number of concurrent BLAH instances is configurable via yaim. The name of the relevant yaim variable is CREAM_CONCURRENCY_LEVEL.

 

0.0.0.1 Tune the BLAH BUpdater polling frequency

 
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