Week of 170612

WLCG Operations Call details

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Tier-1 downtimes

Experiments may experience problems if two or more of their Tier-1 sites are inaccessible at the same time. Therefore Tier-1 sites should do their best to avoid scheduling a downtime classified as "outage" in a time slot overlapping with an "outage" downtime already declared by another Tier-1 site supporting the same VO(s). The following procedure is recommended:

  1. A Tier-1 should check the downtimes calendar to see if another Tier-1 has already an "outage" downtime in the desired time slot.
  2. If there is a conflict, another time slot should be chosen.
  3. In case stronger constraints cannot allow to choose another time slot, the Tier-1 will point out the existence of the conflict to the SCOD mailing list and at the next WLCG operations call, to discuss it with the representatives of the experiments involved and the other Tier-1.

As an additional precaution, the SCOD will check the downtimes calendar for Tier-1 "outage" downtime conflicts at least once during his/her shift, for the current and the following two weeks; in case a conflict is found, it will be discussed at the next operations call, or offline if at least one relevant experiment or site contact is absent.

Links to Tier-1 downtimes

ALICE ATLAS CMS LHCB
  BNL FNAL  

Monday

Attendance:

  • local: Kate (chair, DB, WLCG), Julia (WLCG), Maarten (WLCG, ALICE), Cedric (ATLAS), Vincent (security), Lorena (computing), Andrea M. (MW), Jesus (storage), Marian (network)
  • remote: Chi-Hsun (ASGC), Tommaso (CMS), Dmytro (NDGF), Vincenzo (EGI), Kyle (OSG), David (FNAL), Gareth (RAL), Luca (CNAF), Pepe (PIC)

Experiments round table:

  • ATLAS reports ( raw view) -
    • Activities:
      • Atlas Software and Computing week this week
      • MC simulation + event generation dominating between ATLAS activities
    • Issues:
      • Quiet week
      • fts.usatlas.bnl.gov not reachable : GGUS:12884. Problem was due to DNS
      • 1 AFS volume(s) in project 'atlas' overloaded reported. Due to one user compiling his code from a remote site (Desy)
      • 1 CVMFS Stratum1 ATLAS was degraded for a several time during the week (but OK now)

  • CMS reports ( raw view) -
    • a production-level calm week: no data (scrubbing), tails of Data Rereco. Preparation for 2017 MC
    • having big problems processing raw data for release preparation. Most of the IO intensive jobs crash with Xrd Socket Errors (see GGUS:128888). It happened both at CERN and FNAL, and seems to happen everywhere Xrootd is used.
      • not clear yet where is the problem, but we could replicate it standalone: it happens randomly, but in such a way that a 8 hour job has small chances to reach the end
      • it seems to happen only for IO intensive jobs, so server load seems to have a role
      • testing right now a 2 lines client side patch (basically reverting a previous patch)
    • other notable tickets:
      • GGUS:128809: ~ 1500 lost files at Vanderbilt. Will be reproduced (nothing primary)

  • ALICE -
    • Continued very high activity

Sites / Services round table:

  • ASGC: ntr
  • BNL: nc
  • CNAF:
    • IPv6: tested gridftp and storm, still testing xrootd.
  • EGI: EMI repositories will be shut down on Thursday
  • FNAL: ntr
  • IN2P3: nc
  • JINR: nc
  • KISTI: ntr
  • KIT: nc
  • NDGF: Some ATLAS data might be unavailable for 3 hours tomorrow due to power maintenance on Denmark's storage.
  • NL-T1: After Tuesday's upgrade to dCache 2.16, we had a very slow database, causing many timeouts. We fixed it by doing 'vacuum analyze t_tags' from a cron job. See also GGUS:128869.
  • NRC-KI: nc
  • OSG: Ticket exchange between GGUS and OSG is working again. A meeting on the future of authorization will take place tomorrow.
  • PIC: ntr
  • RAL: Preparing to increase OPN link from 2 * 10Gbit links to 3 * 10Gbit links. Planned for this Wednesday (14th June) - but still to confirm.
  • TRIUMF: NTR

  • CERN computing services: ntr
  • CERN storage services: ntr
  • CERN databases: OS patching of LHCb offline database cluster (Wednesday 10:00-12:00) and ALICE online Active Data Guard (Thursday 14:30-17:30)
  • GGUS:
  • Monitoring: BDII was retired
  • MW Officer: NTR
  • Networks: NTR
  • Security: NTR

AOB:

Maarten commented that future of Globus is being discussed with NSF directly by Ian Bird. Not a crisis, since the SW is open source and a lot of work, including patches has already been done on our side since years; the rpms are built by NorduGrid. Official ownership would be desirable. Alternative software stack should be considered for the future. Julia commented that a higher level discussion on what should be supported and by whom will have to take place. The future of the security stack will e.g. be discussed tomorrow during the meeting mentioned by Kyle.

  • Note: Mon-Thu next week the WLCG Workshop is being held in Manchester.
  • The operations meeting next Mon will be virtual .
  • You may provide relevant incidents, announcements etc. for the operations record.
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Topic revision: r16 - 2017-06-12 - MaartenLitmaath
 
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