-----BEGIN PGP SIGNED MESSAGE----- > running. However, our sysadmin insists that cpu-intensive jobs > will have no effect on I/O intensive jobs. Is this generally true? >
First of all, let me tell you I am no expert :) Its strange that a machine designated as fileserver is running user jobs at all, be they cpu- or io-intensive. A fileserver is supposed to churn out files - fast, and jobs that compete with cpu, memory, or bandwith resources don't belong there. (our fileservers are strictly nologin, nobatch). There is _some_ truth in what you sysadmin says though, in some cases. If the fileserver has plenty of memory, and all jobs fit in memory snugly, cpu-intensive processes should not slow down io-intensive jobs significantly. Except if there are a lot more jobs than CPU's: jobs all get a turn on the CPU but processes that often have to wait for IO might miss out sometimes (not too bad though). If memory is short, then there will be the overhead of swapping. IO-job runs now, has to wait, part of it might be swapped to disk while CPU job takes over for a while, then stuff needs to be reloaded from disk if IO-job gets a turn (and maybe CPU-job gets swapped to disk). A heavily swapping system might slow down significantly - hence your job will run slower. People with long cpu-intensive jobs might also give their job a loweer priority (nice it, or put it in a batch queue), which will give io-restricted jobs a slightly better performance. Anyway, as I said I am not an expert. But this is my understanding how things work. (if you really have to use the fileserver as a batchserver or job-running machine, it might be better to set up proper batchqueues which limit the number of jobs being run simultaneously - and ofcourse give it low priority) With kind regards, - -- drs. Jean-Jack M. Riethoven EMBL Outstation - Hinxton [EMAIL PROTECTED] ICQ#: 3433929 European Bioinformatics Institute Phone: (+44) 1223 494635 Wellcome Trust Genome Campus Fax : (+44) 1223 494468 Hinxton, Cambridge CB10 1SD URL : http://industry.ebi.ac.uk/ UNITED KINGDOM -----BEGIN PGP SIGNATURE----- Version: PGPfreeware 6.5.1 Int. for non-commercial use <http://www.pgpinternational.com> iQCVAwUBObZynFQJC1wdx3D1AQGXUgQAo4I6pity9fojGvHpSS6wsTh3XxXXgQ53 tjBc60k66SsnE7CrJPXNcCfGCRwoWlSCG2ah3Yn0AmJBaboRmD9TrgsqLS5iQDkI TzMY3dPDeDUq8F6iDRgr0FtLylo9x2u1lIqrualnE07KG5uKFf+/qU1iVEIaJkc0 fxAfACHvNS0= =7xj/ -----END PGP SIGNATURE-----