1. DCache Basics Alessandro Usai, Sergio Maffioletti Grid Group CSCS

2. www.cscs.ch Swiss WLCG Experts Workshop – 11/06/2007 @ CSCS DCache General Architecture

3. www.cscs.ch Swiss WLCG Experts Workshop – 11/06/2007 @ CSCS At the core of DCache are subservices (cells) and domains (JVM) sub-services can run in different locations DCache is flexible

4. www.cscs.ch Swiss WLCG Experts Workshop – 11/06/2007 @ CSCS General comments It is all Java based i.e. platform independent (in principle) It is highly configurable (good) but complex (bad)…the documentation could (needs to) be improved, the logs are obscure (if not absent, unless you explicitly increase the debug level) Not easy to maintain upgrades Yaim component not powerful enough (i.e. you do it by hand)

5. www.cscs.ch Swiss WLCG Experts Workshop – 11/06/2007 @ CSCSDCache@CSCS

6. www.cscs.ch Swiss WLCG Experts Workshop – 11/06/2007 @ CSCS In a nutshell Pnfs needs to be mounted by the pool and admin nodes (they need to be authorized) Postgres configured to grant the admin node Thumpers installed by coping /opt/d-cache from the admin node and changing the configuration where required. Data and Control dirs are placed under /data1 and pointed to via sym links CAs and grid-mapfile regular update from CE (via cronjob)

7. www.cscs.ch Swiss WLCG Experts Workshop – 11/06/2007 @ CSCS Our Pools Configuration Read only and write only pools (to balance the load) p2p enabled (files are replicated for load reasons, only cache copies which get deleted if needed) Two movers queues: wan (gridftp) and default (dcap) 10 concurrent transfers at a time se02-lcg with dteam+ops,cms,atlas and se03-lcg with dteam+ops,cms,atlas,lhcb,hone,dech

8. www.cscs.ch Swiss WLCG Experts Workshop – 11/06/2007 @ CSCS Some problems we saw Logging obscure (difficult to troubleshoot) Domains duplication (as a result we got on board default configuration and a performance hit) Timeouts (a known problem still under investigation within the community) Various authentication problems due to misconfigurations (e.g. wrong VO tags)

9. www.cscs.ch Swiss WLCG Experts Workshop – 11/06/2007 @ CSCS How are we doing just now? How are we doing just now?

10. www.cscs.ch Swiss WLCG Experts Workshop – 11/06/2007 @ CSCS Tips and Advices Recommended: increase the logging level Install srmwatch (beware of the security holes though ) Get acquainted with the ssh interactive shell on the admin node (ssh -l admin -c blowfish -p 22223 localhost) The dcache admin web page is very useful (http://storage01-lcg.projects.cscs.ch:2288/)http://storage01-lcg.projects.cscs.ch:2288/ In case off problems user-forum@dCache.ORG

11. www.cscs.ch Swiss WLCG Experts Workshop – 11/06/2007 @ CSCSReferences http://twiki.cscs.ch/twiki/bin/view/LCGTier2/CSCSDCACHE_ausai http://www.dcache.org/ http://www.dcache.org/manuals/workshop2007/ndgf.shtml