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Opening xrootd files #4

Open knoepfel opened 3 years ago

knoepfel commented 3 years ago

This issue has been migrated from https://cdcvs.fnal.gov/redmine/issues/23689 (FNAL account required) Originally created by @hgreenlee on 2019-12-03 18:01:46

Is it possible to make RootInput more robust against xrootd failures when opening xrootd files? One failure mode that I think happens is that if you try to open an xrootd file for streaming, and the root file is not staged, the time to stage the file may be longer than the xrootd timeout. There may be other kinds of glitchy xrootd failures. Here are some possible feature enhancements.

  1. Check the dCache locality of a root file before trying to open using xrootd.
  2. More robust retry machanisms.
knoepfel commented 3 years ago

Comment by @knoepfel on 2019-12-09 20:10:27

Herb, please look at the comments in Redmine issue 21638. As ROOT is the client of XRootD in this particular case, XRootD behavior is controlled based on ROOT's use of XRootD. Hopefully there is enough flexibility described in Redmine issue 21638 to mitigate the issues you've encountered.

Also, note that roughly 1 year ago, some errors were fixed with art's handling of XRootD failures (see Redmine issue 21289). Unfortunately, there are some errors (e.g. authentication errors) where the timeout window is not configurable.

That said, I know that this can be a frustrating issue, so I will schedule a meeting in the near future with you and others to help go through the desired features/bug fixes to make the art's ROOT file-handling easier to use.