Week of 170821

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: Luca (SCOD+Storage), Kate (CMS+DB), Yulia (WLCG), Vincent (Security), Andrea M. (MW), Nilo (DB), Ben and Emmanouil (Computing), Michal (ATLAS), Marian (Network), Alberto (Monitoring)
  • remote: Ken (CMS), Luca (LHCb), Xin (BNL), Luca (CNAF), Vincenzo (EGI), Christian (NDGF), Dennis (NL-T1), Elizabeth (OSG), John (RAL), Di (TRIUMF)

Experiments round table:

  • ATLAS reports ( raw view) -
    • Activities:
      • normal activities
    • Problems
      • Jobs at CERN-PROD_T0_4MCORE fail with "cannot import name mkstemp" (GGUS:130139) - caused by one bad WN
      • permission denied job failures at Taiwan (GGUS:130098) - problem with xrootd shared key
      • Transfer failures at RAL-LCG2-ECHO (GGUS:130138) - Ceph bug, patch will be applied in the beginning of the week

  • CMS reports ( raw view) -
    • The total solar eclipse will be maximal in Lincoln just five hours after this meeting! Hoping the weather will stay clear.....
    • To my knowledge the T0 EOS problems have not been a problem this week, but I'll take any updated information here.
    • Prompt reconstruction was paused for a couple of days while awaiting a new software release, but now back running normally.
    • T1_US_FNAL data transfer problems should be resolved now.
    • We now have many more processing requests in the system, have been using > 150K cores steadily all week
    • GGUS:130097 -- problems with internal data movement at KIT? No, probably not, it's understood.
    • GGUS:130078 -- CCIN2P3 not approving new data transfers from T0. Just a coverage gap due to August vacations, figured out, subscriptions approved, no problem.

    • UPDATE on T0-EOS from Luca
      • patches and workaround have been applied during the second week of August
      • from Friday 11th Aug at 12:00 the EOSCMS instance is considered to be "fixed"
      • on Monday 14th Aug at 14:00 the namespace was "cold booted" to make vanished directories reappear
      • there is an ongoing recovery process to re-upload part of the data affected

  • ALICE -
    • Apologies: ALICE operations will not attend today
    • Continued very high activity

  • LHCb reports ( raw view) -
    • Activity
      • Monte Carlo simulation, data processing and user analysis
    • Site Issues
      • T0: Problem with EOS in the night between fri and sat (GGUS:130137). Become an alarm in the morning of sat. Fixed now, 3/7 grid-ftp doors were mis-behaving
      • T1: NTR

Sites / Services round table:

  • ASGC:
  • BNL: chasing a dark data issue last week, turned out to be due to latency of dCache SrmSpaceManager updating its database. When there are high volume of deletion requests, this latency causes "dark data" to show up for a day or two, although the data is already removed from disk.
  • CNAF: Transfer problem with CBPF solved by adjusting the MTU settings on Brazilian side.
  • EGI: NTR
  • FNAL:
  • IN2P3:
  • JINR:
  • KISTI:
  • KIT:
  • NDGF: NTR
  • NL-T1: On Thursday the tape back-end at SURFsara will be upgraded. During this maintenance all data on tape will be inaccessible. Details are in the GOCDB.
  • NRC-KI:
  • OSG:NTR
  • PIC:
  • RAL: We are currently patching the Ceph/Echo instance to fix the problems mentioned in the Atlas report. The production FTS Database server was moved to a new hyperV infrastructure this morning.
  • TRIUMF: NTR

AOB:

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Topic revision: r20 - 2017-08-24 - AndreaManzi
 
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