CernVM virtual workshop 2021, 1–2 February 2021
ATLAS, ALICE, LHCb
Searching for dark matter
R&D for testing and prototyping a new gravitational wave detector
Partnering with SURFsara to form a LHC Tier 1 since 2001.
Partnership evolved into a shared national infrastructure for large-scale science computing.
This is well beyond the scope of Nikhef's own mission, but strategically important for a sustainable computing infrastructure.
We run a stratum 0 server for a long time and it is in need of an upgrade from CentOS 6 to CentOS 7. This is currently on-going.
The only repository of note that we have at the Stratum 0 is softdrive.nl.
The stratum 1 server has been recently upgraded to CentOS 7. Icinga monitoring is in place, the system has a frontier-squid reverse proxy monitored by CERN.
We carry a bunch of repos from opensciencegrid.org, gridpp.ac.uk and egi.eu.
On purpose we did not include the CERN repos.
The hardware is fully virtual, with a iscsi storage backend on a Fujitsu DX200 flexible tiering storage system. Not the ideal match, but it scales well enough so far.
Current disk use is 6.6TB, coming down from 11TB pre-upgrade. The difference is probably due to no garbage collection.
Icinga sensor tracks every repository on every node.
Only occasional (mostly transient) warnings reported.
SERVICE STATUS: 1 I/O errors detected; repository revision 4958
Usually a manual
cvmfs_config reload gets things unwedged.
On very rare occasions a system won't be able to recover from a CVMFS error and will need a reboot. These have been fewer with later versions of CVMFS.
Just recently the upgrade from 2.7.2 to 2.7.5 caused a handful of our worker nodes to hang; they needed to be drained and rebooted.
The ligo.osgstorage.org repository is different as data is not public.
Requires use of x509 helper library and authenticated user.
Actual data coming from stashcache.
CVMFS 'for the rest of us'; users manage their own directories on this repository.
Co-developed with SURFsara.
Nightly garbage collection (currently broken)
Nested catalogs for bigger users (and the monitoring user which triggered a revision every 5 minutes). This overcame the biggest performance hurdle.
Recently used to include unpacked singularity images (as a proof-of-concept).
The Spider system at SURFsara is a high-throughput data processing platform, similar to Grid but with a broader scope and service offering.
Projects can port their software easily between Grid and Spider using softdrive.nl.
SURFsara advisors have been helping applications to get their software onto different platforms with softdrive.nl.
Upgrading the Stratum-0 immediately.
Explore the possibilities for unpacked container images, template transactions, and the ephemeral writable shell.
Keeping things going with minimal effort.