Week of 161121

WLCG Operations Call details

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  • The purpose of the meeting is:
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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: Maria Alandes (chair and minutes), Julia Andreeva (WLCG), Maarten Litmaath (ALICE), Giuseppe Bagliesi (CMS), Vincent Brillault (Security), Nilo Segura (DB), Herve Rousseau (Storage), Alexei (LHCb)
  • remote: Fahui Lin (ASGC), Vincenzo Spinoso (EGI), Dave Mason (FNAL), Rolf Rumler (IN2P3), Dimitry (KIT), Ulf Tigerstedt (NDGF), Eygene Ryabinkin (NRC-KI), Kyle Gross (OSG), Jose Flix (pic), Di Qing (TRIUMF), Andrzej Olszewski (Atlas), Luca Lama (CNAF)
  • excused: Alberto Aimar (Monitoring), Maria Dimou (GGUS)

Experiments round table:

  • ATLAS reports ( raw view) -
    • Reprocessing of physics delayed stream was running taking data from tape directly.
      • Slow at the beginning, due to Panda using not evenly tape resources, putting too much load on CERN tapes.
      • Additional staging requests from Tier0 activities (running re-calibration before large rel. 21 reprocessing of 2015+2016 data).
      • There was also competition of download requests from users. Limits has been temporary reduced to 1TB/day. To be discussed with CREM.
      • Measures have been taken to have staging from tapes more distributed over all Tier1s. This helped reprocessing already over the weekend.
    • Slow recovery of disk space reported by some dCache instances (FZK, RRC-KI) after file deletion by ATLAS. Not clear if this is dCache service issue or site problem. Discussing with dCache support.
    • CVMFS service at TAIWAN is getting behind regularly in updating to latest version of contents.

The CVMFS issue at Taiwan is discussed at the meeting:

  • Experiment package updates may be absent or late, presumably due to network issues
  • Observed by ATLAS and ALICE
  • The biggest ALICE sites in Asia have bypassed the Stratum-1 at ASGC to avoid random job failures
  • The CVMFS developers intend to make the client yet more robust in failing over to other instances when the default Stratum-1 cannot deliver the requested file for whatever reason
  • They also provided test commands that a pilot could run to check the health of the local CVMFS setup
    • Before committing to a user payload

  • CMS reports ( raw view) -
    • Heavy Ion data taking ongoing
    • Digi-Reco campaign for Moriond 2017 ongoing (multi-core jobs efficiency is not yet optimized )
    • Problems during the week
      • significant cmsweb scaling issues causing various problems, solutions being investigated/tested
      • ELOG (cms-logbook.cern.ch) not responsive, sessions expiring very soon with login re-prompt GGUS:125043 (solved)
      • CRAB3
        • problems with corrupted ASO couchDB database, working fine after scratching and rebuild of DB
        • six new schedulers added to a better submission handling
      • Dashboard
        • not updating for several days due to a SAM3 machine running out of disk space, slowly recovering GGUS:125037
        • links malfunctioning due to LCGR Oracle cluster down on Friday ~15:00 GGUS:125089

  • ALICE -
    • NTR

  • LHCb reports ( raw view) -
    • Activity
      • Monte Carlo simulation, data reconstruction/stripping and user jobs on the Grid
    • Site Issues
      • T0:
        • NTR
      • T1:
        • NTR

Sites / Services round table:

  • ASGC: NTR
  • BNL: NA
  • CNAF: NTR
  • EGI: NTR
  • FNAL: Dave informs the successful extension of FNAL computing capacity by using the HEP Cloud project with 150K cores during 4 days.
  • GridPP: NA
  • IN2P3: NTR
  • JINR: Backlog in tape reading queue. Now optimizing our robot for reading from tapes.
  • KISTI: NA
  • KIT: NTR
  • NDGF: The disk pool that failed next week will be replaced this week. Cause not yet understood.
  • NL-T1: NA
  • NRC-KI: had a dropped-off LHCb dCache pool at the week-end due to too many clients overloading it. Fixed at Monday morning.
  • OSG: Kyle asks a question on how to reroute CMS GGUS tickets that will be followed up offline with Giuseppe.
  • PIC: Downtime during the 13th of December to upgrade dCache, tape and batch.
  • RAL: NTR
  • TRIUMF: NTR

  • OTG:0034178: TWiki Upgrade 22.11.2016 from 7h30 to 9h00. Read-only mode during the intervention.
  • CERN computing services: NA
  • CERN storage services:
    • CMS: Hard(er) Throttling of AAA accesses to T0 data to protect EOSCMS instance (GGUS:125076 and GGUS:125061)
  • CERN databases:
    • OTG:0034208: LCGR db service severely degraded on 18.11.2016 from 15h00 to 20h00. A block corruption that affected a table in COSMIC@LCG database system, triggered a partial downtime in the LCG database. The oracle background process that tried to recover the block, finally collapsed. This caused the whole instance (LCGR4) to die as well. Unfortunately, the other instances (LCGR1-LCGR3) also tried to perform the same recovery and failed, leading to full crash of the 4-node cluster. After contacting with Oracle with a Severity 1 ticket, we managed to start one of the instances (disabling the automatic recovery). We tried to recover/bypass the table, but in the end and after consulting with the COSMIC owner, we removed the table completely. The table is not a critical one (kind of internal logging of the application), so we will extract it from the backup and get only the data that is needed.
  • GGUS: Release next week, on Wed 30/11 with ALARM tests as usual.
  • Monitoring: ("sorry I have another meeting this week. Alberto")
    • Final reports for the October 2016 availability were sent around
    • Link to MONIT portal: http://monit.cern.ch
  • MW Officer: NTR
  • Networks:
    • OTG:0033966: Wigner GEANT maintenance on 22.11.2016 at 21h00 to 23.11.2016 at 3h00.
  • Security: No news on CVE-2016-7117 for RHEL.

AOB:

Topic attachments
I Attachment History Action Size Date Who Comment
Unknown file formatpptx GGUS-for-MB-Nov-16.pptx r1 manage 2850.3 K 2016-11-21 - 11:17 MariaDimou GGUS Slide for the 22/11 MB - Tickets for 5 weeks
Edit | Attach | Watch | Print version | History: r21 < r20 < r19 < r18 < r17 | Backlinks | Raw View | WYSIWYG | More topic actions
Topic revision: r21 - 2016-11-22 - MariaALANDESPRADILLO
 
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