Tier1 Operations Report 2016-01-06

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RAL Tier1 Operations Report for 6th January 2016

Review of Issues during the fortnight 23rd December 2015 to 6th January 2016.
  • There were significant batch problems during the first part of this fortnight. Problems had been progressively getting worse. These problems were resolved between Christmas and the New Year. The problems were found to be partly excessive load on the Condor components running on the ARC CEs. This load coming from the new draining algorithm. There was an additional problem caused by a parameter change introduced with a Condor update.
  • Over the holiday period we were running with 2*10Gbit link for the "bypass" route that is used by data traffiuc that does not use the OPN. However, it was found that the ACLs that act as a firewall over this route were not in place. There have been problems this week as we have attempted to put the ACLs back in place and still run with the 2*10Gbit link. There were significant problems during last night (5-6 Jan). We have now reverted to a single 10Gbit link for this connection.
  • Over the new year (31/12-01/01) AtlasDataDisk filled up. This caused the Atlas SAM tests to fail. There was very high load on the couple of servers that did have some remaining space - which in turn led to read failures as well. The problem s was alleviated when Atlas changed their deletion algorith on the 2nd Jan to preferentially delete larger files first and free space became available.
  • There was a problem with all Castor instances during the day on Monday 4th January when there were internal problems within Castor. The problem lasted roughly the length of the working day but is not yet understood.
Resolved Disk Server Issues
  • GDSS665 (AtlasTape) failed on the 21st Dec. It was rebooted and all canbemigr files migrated to tape. There wasa bad disk that was replaced. Returned to production on Christmas Day!
  • GDSS620 (GenTape - D0T1) failed on the 22nd Dec. It was rebooted and all canbemigr files migrated to tape. Following testing it was put back into service on the 24th December. (But note that it has since failed yet again).
  • GDSS656 (lhcbRawRdst - D0T1) has a double disk failure on the 23 Dec. It has been removed from service while the disks are replaced and RAID rebuilt. It was returned to service on the 24th December.
  • GDSS675 (CMSTape - D0T1) failed on the afternoon of 23rd December. A faulty drive was found. Also returned to production on Christmas day.
  • GDSS770 (AtlasDataDisk - D1T0) crashed on the 31st December. Following checks it was returned to service later that day.
  • GDSS710 (CMSDisk - D1T0) Failed on teh 2nd January. Following checks it was returne dto service the following day.
  • GDSS648 (LHCb -User - D1T0) was taken out of service on the 4th January as two disks had failed. Returned to production the following day.
  • GDSS707 (AtlasDataDisk - D1T0) Was taken out of service on teh 4th January - one of the Castor processes was failing to run. Following investigations it was returned to production in read-only mode the next day.
Current operational status and issues
  • There is a problem seen by LHCb of a low but persistent rate of failure when copying the results of batch jobs to Castor. There is also a further problem that sometimes occurs when these (failed) writes are attempted to storage at other sites. A recent modification has improved, but not completed fixed this.
  • The intermittent, low-level, load-related packet loss seen over external connections is still being tracked. Likewise we have been working to understand some remaining low level of packet loss seen within a part of our Tier1 network.
  • There is a problem reported by LHCb of a high rate of batch job failures since around the 9th December. The cause is not yet known.
Ongoing Disk Server Issues
  • GDSS620 (GenTape - D0T1) failed on the first January. This server has failed before recently. Investigations ongoing.
  • GDSS677 (CMSTape - D0T1) failed yesterday evening (5th Jan). It is being worked on.
Notable Changes made since the last meeting.
  • Following problems the 'bypass' network link has been dropped back to a single 10Gbit link.
  • The new batch draining script has been modified to eliminate load on Condor.
Declared in the GOC DB

None

Advanced warning for other interventions
The following items are being discussed and are still to be formally scheduled and announced.
  • Upgrade of remaining Castor disk servers (those in tape-backed service classes) to SL6. This will be transparent to users.

Listing by category:

  • Databases:
    • Switch LFC/3D to new Database Infrastructure.
  • Castor:
    • Update SRMs to new version (includes updating to SL6).
    • Update disk servers in tape-backed service classes to SL6 (ongoing)
    • Update to Castor version 2.1.15.
  • Networking:
    • Make routing changes to allow the removal of the UKLight Router.
  • Fabric
    • Firmware updates on remaining EMC disk arrays (Castor, LFC)
Entries in GOC DB starting since the last report.
Service Scheduled? Outage/At Risk Start End Duration Reason
srm-atlas.gridpp.rl.ac.uk, UNSCHEDULED WARNING 01/01/2016 04:30 01/01/2016 12:27 7 hours and 57 minutes one of four machines in DNS alias down, so some transfer failures possible
Open GGUS Tickets (Snapshot during morning of meeting)
GGUS ID Level Urgency State Creation Last Update VO Subject
118631 Green Very Urgent Waiting Reply 2016-01-05 2016-01-06 Atlas RAL-LCG2 'unable-to-connect' destination transfer errors
118573 Green Urgent In Progress 2016-01-02 2016-01-05 Atlas A lot of RAL-LCG2 data transfers fails
118549 Green Urgent Waiting for Reply 2015-12-30 2016-01-05 CMS Volume Idle about 100% of Volume Requested at T1_UK_RAL
118494 Green Urgent In Progress 2015-12-23 2015-12-24 CMS Xrootd problems???
118209 Green Less Urgent In Progress 2015-12-15 2015-12-18 Enabling CVMFS for the vo.neugrid.eu VO
118044 Green Less Urgent Waiting Reply 2015-11-30 2016-01-05 Atlas gLExec hammercloud jobs failing at RAL-LCG2 since October
117846 Green Urgent Waiting for Reply 2015-11-23 2015-12-22 Atlas ATLAS request- storage consistency checks
117683 Green Less Urgent In Progress 2015-11-18 2016-01-05 CASTOR at RAL not publishing GLUE 2
116866 Amber Less Urgent On Hold 2015-10-12 2015-12-18 SNO+ snoplus support at RAL-LCG2 (pilot role)
116864 Red Urgent In Progress 2015-10-12 2015-12-16 CMS T1_UK_RAL AAA opening and reading test failing again...
Availability Report

Key: Atlas HC = Atlas HammerCloud (Queue ANALY_RAL_SL6, Template 508); CMS HC = CMS HammerCloud

Day OPS Alice Atlas CMS LHCb Atlas HC CMS HC Comment
23/12/15 100 100 100 96 100 100 100 Single SRM test failure. Could not find the test file.
24/12/15 100 100 97 100 100 100 100 SRM failure: File deletion failed in token. Error message: __main__.TimeoutException
25/12/15 100 100 100 100 100 96 100
26/12/15 100 100 100 100 100 100 100
27/12/15 100 100 100 100 100 100 100
28/12/15 100 100 100 100 100 86 100
29/12/15 100 100 100 100 100 0 100
30/12/15 100 100 100 100 100 0 100
31/12/15 100 100 92 96 100 100 100 CMS: Single SRM failure. Atlas: AtlasDataDisk full
01/01/16 100 100 6 100 100 55 100 AtlasDataDisk full
02/01/16 100 100 40 100 100 94 100 AtlasDataDisk full
03/01/16 100 100 100 100 100 97 N/A
04/01/16 96.1 100 80 85 85 100 100 Internal communication problem (or something) affected Castor.
05/01/16 99.6 100 68 68 68 91 N/A Problem on the Bypass (non-OPN) link.