RAL Tier1 Operations Report for 6th January 2016
Review of Issues during the fortnight 23rd December 2015 to 6th January 2016.
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- On Thursday 10th December there was a significant problem on the Tier1 network. A packet storm was followed by the Tier1 network being disconnected from the site network. The trigger appears to have been the restarting of a particular switch. The details of this are not yet understood.
- There was a problem with the recall from tape of a large number of files for LHCb over the weekend of 11/12/13 Dec. This was caused by some poor performance of at least one of the disk servers in the disk cache and a parameter introduced in the Castor 2.1.15 tape servers that delayed the reporting of when files were read from tape.
Resolved Disk Server Issues
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- GDSS675 (CMSTape - D0T1) failed in the early hours of 8th Dec. On investigation found there were two disks that had failed. Returned to production on 11th December.
- GDSS620 (GenTape - D0T1) also failed during the early morning of 8th Dec. Also returned to production on the 11th Dec. No cause found.
- GDSS689 (AtlasDataDisk - D1T0) was taken out of production on the 10th Dec. when a second disk failed during the rebuilding of a first. Returned to production after the first disk rebuild had completed on Tuesday 15th Dec.
- GDSS654 (LHCbRawRDst - D0T1) was taken out of service on the 11th Dec. Again a precaution as a double disk failure. Returned to production on the 13th Dec.
- GDSS617 (AliceDisk -D1T0) Crashed on the 15th Dec. After tests no underlying cause found. Returned to production on the 17th Dec.
- GDSS710 (CMSDisk - D1T0) Taken out of production for a short while for a reboot as the RAID card was not seeing a replacement disk.
- GDSS686 (AtlasDataDisk - D1T0) Taken out of production on the 21st Dec. as there was double disk failure. Returned to production on the 22nd after the first disk had rebuilt.
Current operational status and issues
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- 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
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- GDSS665 (AtlasTape) failed on the 21st Dec. It was rebooted and all canbemigr files migrated to tape. It is undergoing tests.
- GDSS620 (GenTape - D0T1) failed again (see above) on the 22nd Dec. It was rebooted and all canbemigr files migrated to tape. It is undergoing tests.
- 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.
Notable Changes made since the last meeting.
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- The final steps have been taken for the removal of the old core network switch which has now been taken off the network.
- A board has replaced in the UKLight router and another added. Following this the link between the UKLight router and the RAL border router was doubled from a single to a pair of 10Gbit connections. Thus doubling our data bandwidth over this route.
- In order to ease problems with tape recalls servers in the LHCbRawRDst service class were converted to use the Linux NOOP IO scheduler.
None
Advanced warning for other interventions
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The following items are being discussed and are still to be formally scheduled and announced.
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- 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.
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Service
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Scheduled?
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Outage/At Risk
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Start
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End
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Duration
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Reason
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srm-atlas.gridpp.rl.ac.uk,
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UNSCHEDULED
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WARNING
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01/01/2016 04:30
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01/01/2016 12:27
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7 hours and 57 minutes
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one of four machines in DNS alias down, so some transfer failures possible
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Open GGUS Tickets (Snapshot during morning of meeting)
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GGUS ID |
Level |
Urgency |
State |
Creation |
Last Update |
VO |
Subject
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118631
|
Green
|
Very Urgent
|
Waiting Reply
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2016-01-05
|
2016-01-06
|
Atlas
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RAL-LCG2 'unable-to-connect' destination transfer errors
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118573
|
Green
|
Urgent
|
In Progress
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2016-01-02
|
2016-01-05
|
Atlas
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A lot of RAL-LCG2 data transfers fails
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118549
|
Green
|
Urgent
|
Waiting for Reply
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2015-12-30
|
2016-01-05
|
CMS
|
Volume Idle about 100% of Volume Requested at T1_UK_RAL
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118494
|
Green
|
Urgent
|
In Progress
|
2015-12-23
|
2015-12-24
|
CMS
|
Xrootd problems???
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118209
|
Green
|
Less Urgent
|
In Progress
|
2015-12-15
|
2015-12-18
|
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Enabling CVMFS for the vo.neugrid.eu VO
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118044
|
Green
|
Less Urgent
|
Waiting Reply
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2015-11-30
|
2016-01-05
|
Atlas
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gLExec hammercloud jobs failing at RAL-LCG2 since October
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117846
|
Green
|
Urgent
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Waiting for Reply
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2015-11-23
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2015-12-22
|
Atlas
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ATLAS request- storage consistency checks
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117683
|
Green
|
Less Urgent
|
In Progress
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2015-11-18
|
2016-01-05
|
|
CASTOR at RAL not publishing GLUE 2
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116866
|
Amber
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Less Urgent
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On Hold
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2015-10-12
|
2015-12-18
|
SNO+
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snoplus support at RAL-LCG2 (pilot role)
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116864
|
Red
|
Urgent
|
In Progress
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2015-10-12
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2015-12-16
|
CMS
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T1_UK_RAL AAA opening and reading test failing again...
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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.
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