Job output (number of open files)

[adewit]

The IC disk server doesn't really like too many files being open at the same time, which means running systematic shifts as well as the central values from the same job makes vols super slow (and our colleagues who then can't do any work super annoyed). Can work around this by running syst shifts separately, but at some point should investigate better options, for example writing a separate tree for each shift into one file, then writing them to separate files after the jobs finish. Not sure this would actually be better than current workaround/wouldn't overload the disk server in some other way, but we should check.