Brian Paul Bockelman (University of Wisconsin Madison (US)), Maria Arsuaga Rios (CERN), Petr Vokac (Czech Technical University in Prague (CZ))

Topic: WLCG DOMA BDT Meeting

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Meeting ID: 998 3605 7922
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Meeting ID: 998 3605 7922
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    • 1
      Hot topics

      Starting with next (16 March 2022) WLCG DOMA BDT meeting we are going to use different Zoom room (integrated with CERN Indico).

      SRM/HTTP Update (Petr)

      • CMS has moved its FTS to enable WebDAV + SRM/HTTPS (n.b. - in time for the tape exercise!)
      • FTS team is considering to enable this by default as there are few experiments who need this disabled.
      • Any issues arising?
        • Issues with DAVIX writing a temporary file on FTS server.  Probably FTS streaming issues.  Suggest FNAL ensures streaming is disabled.


    • 2
      Packet marking
      Speakers: Marian Babik (CERN), Shawn Mc Kee (University of Michigan (US))
      • Packet marking is part of the "SciTags" activity in the Research Network Technical WG.  95 members from 50 orgs.
      • Primary goal: allow tracking and correlation of transfers with R&E network provider's network flow monitoring.
        • Can associated flows with a specific experiment or activity.
        • Provides sites with more visibility into network flows.
      • How tags works:
        • Packet marking: markers are added to each packet.
        • Flow marking: UDP firefly sent out periodically, associated with the flow.
        • Network-level collectors at the respective entities collect fireflies or examine packets; hook into the respective analytic platforms.
        • See: https://www.scitags.org/api.json
      • WLCG:
        • Experiment-level systems have knowledge, pass it to FTS3.
      • Status:
        • Flow marking works with IPv6 and IPv4, hence is the focus.
        • XRootD 5.4.0 supports UDP fireflies.
          • N.b. - XRootD docs: https://xrootd.slac.stanford.edu/doc/dev54/xrd_config.htm#_Toc88514010
        • External-to-storage script based on netstat information.
        • ESNet and Jisc/Janet have deployed collectors.
        • Simplified deployment was done during the last data challenge.  Able to correlate UDP fireflies with netflow data.
      • Various additional links to the project on the slides.
      • Discussion:
        • Does the prototype work with HTTP?  A: Yes (Brian thinks it might not work with HTTP push)
        • Technical discussion - note that the fireflies are only sent at beginning and end?
        • Timeline?  DC2023.
        • Who is onboard?
          • ATLAS is enthusiastic, others are backing / provide interest.
        • What about dCache?
          • Currently used the netstat version.
          • dCache team is aware of the activity but not clear if there's a timeline yet.  ACTION ITEM: Need to get input from Tigran.
        • How are flows marked precisely?  E.g., HTTP headers?  TBD.


    • 3
      Token Authorization testbed
      Speaker: Francesco Giacomini (INFN CNAF)
      • See attached slides.
      • Current testbed gets nightly and also Jenkins integration
      • Walked through last night's results.
      • Open issues:
        • Assumes use of issuer implies group membership.  Decision: must be explicit
        • Group vs Scopes.  Decision: both.
      • XRootD failures:
        • There are some open items, mostly around the HTTP status codes.
        • ACTION ITEM: Organize a discussion with Francesco, Brian, Elvin (maybe, TBC), and someone from RAL.  James Walder.
    • 4
      Tape REST access
      Speaker: Cedric Caffy (CERN)
      • Last Friday, finished the discussions of the REST API.
      • Not switching to doing the REST API reference doc to capture the agreed approach "on paper".
      • CERN CTA prototype is working to implement the final draft.
    • 5
      • CMS reconfigured to TAPE transfers to SRM+HTTPS
      • CERN FTS3 public instance will be reconfigured to also prefer HTTPS for as SRM TURL protocol (RQF1986690)



      Tokens and testing (Maria):

      • Can we retire the HTTP-TPC nightly email?  Effectively already done due to technical issues but we can probably just retire this as HTTP-TPC is in production.
        • https://github.com/paulmillar/http-tpc-utils
      • Should we commission a XRootD protocol testbed?  Probably too early - need more agreement on the approach.
        • Recap of discussion on XRootD ZTN GitHub issue: https://github.com/xrootd/xrootd/issues/1584