Difference between revisions of "Tier1 Operations Report 2015-12-09"

Revision as of 10:08, 9 December 2015

Review of Issues during the week 2nd to 9th December 2015.

We ran with a single 10Gbit link between the Tier1 core network and the UKLight router overnight Thursday-Friday 26-27 Nov. The link was saturating. The problem was fixed during the Friday morning with the second 10Gbit link being re-established.
Three disk servers in AtlasDataDisk crashed during last weekend. This appears to be coincidence - this is our largest disk pool. The types of crash appear similar being in the CPUs. A BIOS update is being applied as this may improve the handling of this type of error. This morning these servers were briefly taken down one after the other for a BIOS update (which may improve the handling of this type of fault).

Resolved Disk Server Issues

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.

Ongoing Disk Server Issues

GDSS687 (AtlasDataDisk - D1T0) failed on Friday (4th December) with a read-only filesystem. Taken out of production. It was returned to service in read-only mode the following day. The problem looks to have been was triggered by a disk failure.
GDSS675 (CMSTape - D0T1) failed in the early hours of yesterday morning (8th Dec). This also reported a read-only file system.
GDSS620 (GenTape - D0T1) also failed during the early morning yesterday (8th Dec) - also with a read-only file system.

Notable Changes made since the last meeting.

Work has continued towards removing the old core network switch:
- On Tuesday morning (8th Dec) the network link to the UKLight router was moved. As part of this the connection was increased from 2*10Gbit to 4*10Gbit. (But note one of these four has since given some problems).
- This morning the link to the Castor headnodes was moved.

Declared in the GOC DB

Service	Scheduled?	Outage/At Risk	Start	End	Duration	Reason
All Castor (All SRM endpoints)	SCHEDULED	WARNING	09/12/2015 09:30	09/12/2015 10:30	1 hour	Warning on Castor services for short network reconfiguration.
All Castor (All SRM endpoints)	SCHEDULED	WARNING	08/12/2015 09:00	08/12/2015 10:00	1 hour	Warning on Castor services during short network reconfiguration that affects the external data path to/from the Castor storage.

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.
There is one final step to be made to remove the old 'core' switch from our network. This is expected to be completed this week.
Roll-out of the changed algorithm for the draining of worker nodes to make space for multi-core jobs. The new version allow "pre-emptable" jobs to run in the job slots until they are needed.

Listing by category:

Databases:
- Switch LFC/3D to new Database Infrastructure.
Castor:
- Update SRMs to new version (includes updating to SL6).
- Update disk servers to SL6 (ongoing)
- Update to Castor version 2.1.15.
Networking:
- Complete changes needed to remove the old core switch from the Tier1 network.
- 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
All Castor	SCHEDULED	WARNING	09/12/2015 09:30	09/12/2015 10:30	1 hour	Warning on Castor services for short network reconfiguration.
All Castor	SCHEDULED	WARNING	08/12/2015 09:00	08/12/2015 10:00	1 hour	Warning on Castor services during short network reconfiguration that affects the external data path to/from the Castor storage.

Open GGUS Tickets (Snapshot during morning of meeting)


GGUS ID	Level	Urgency	State	Creation	Last Update	VO	Subject
118044	Green	Less Urgent	In Progress	2015-11-30	2015-11-30	Atlas	gLExec hammercloud jobs failing at RAL-LCG2 since October
117846	Green	Urgent	In Progress	2015-11-23	2015-11-24	Atlas	ATLAS request- storage consistency checks
117683	Green	Less Urgent	In Progress	2015-11-18	2015-11-19		CASTOR at RAL not publishing GLUE 2
116866	Yellow	Less Urgent	In Progress	2015-10-12	2015-11-30	SNO+	snoplus support at RAL-LCG2 (pilot role)
116864	Amber	Urgent	In Progress	2015-10-12	2015-11-20	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
02/12/15	100	100	100	100	100	100	100
03/12/15	100	100	100	100	100	100	100
04/12/15	100	100	100	100	100	100	N/A
05/12/15	100	100	100	100	100	100	100
06/12/15	100	100	97	100	100	100	100	Single SRM Test failure on Put: (Unable to issue PrepareToPut request to Castor)
07/12/15	100	100	100	100	100	100	100
08/12/15	100	100	100	100	96	100	100	Single SRM Tes failure on List: (No such file or directory.)

@@ Line 57: / Line 57: @@
 |}
 * Work has continued towards removing the old core network switch:
-** On Tuesday morning (8th Dec) the network link to the UKLight router was moved. As part of this the links was increased from 2*10Gbit to 4*10Gbit. (But note one of these four has since given some problems).
+** On Tuesday morning (8th Dec) the network link to the UKLight router was moved. As part of this the connection was increased from 2*10Gbit to 4*10Gbit. (But note one of these four has since given some problems).
 ** This morning the link to the Castor headnodes was moved.
 <!-- *************End Notable Changes made this last week************** ----->