CMS Requirements for CVMFS, Frontier and Xrootd
Here is a list of CMS requirements/recommendations for the services to be deployed by the end of this year (2012).
This is not an official CMS document. I'm trying to summurize for my own purposes all the information that I could find so far.
CVMFS
CMS recommendations for the CVMFS deployment
https://twiki.cern.ch/twiki/bin/view/CMSPublic/CernVMFS4cms
Worker node
"Present recommendation is to put the cache on a separate partition and
make the cache at least 6GB large."
https://hypernews.cern.ch/HyperNews/CMS/get/t2/834/2/1/1.html
Squid cache server
"CVMFS tends to put a very light load on a squid, much lighter than Frontier."
https://hypernews.cern.ch/HyperNews/CMS/get/t2/834/2.html
CMSSW disk usage
Disk space used by the 64-bit CMSSW releases:
37G for 12 slc5_amd64_gcc462 releases => 3GB/release
64G for 31 slc5_amd64_gcc434 releases => 2GB/release
Frontier
Installing Frontier Local Squid Cache Server
https://twiki.cern.ch/twiki/bin/view/CMS/SquidForCMS
"For most purposes 2GHZ, 2GB, 100 GB should be adequate."
"Squid on one core of a modern CPU can pretty much keep up with 2 gigabits."
"Sites with over 500 job slots should have at least 2 squids for reliability."
Xrootd
CMS Xrootd Architecture
https://twiki.cern.ch/twiki/bin/view/Main/CmsXrootdArchitecture
CMS Xrootd service hardware recommendations:
https://twiki.cern.ch/twiki/bin/view/Main/XrootdHardware
There are two options for enabling fallback:
- Reading files via NAT or public internet: This is done by almost all sites, and can be done with a traditional NAT. If you see 1Gbps of traffic from Xrootd for fallback use, you almost certainly have an issue with your storage system.
- Xrootd Proxy: This will be done for the CMS HLT farm. Stephen Gowdy is preparing a recipe in the upcoming weeks. Hardware requirements will be similar to the ones for Xrootd covered above. Performance for jobs will be severely degraded compared to the NAT, pending a few required performance patches in a future Xrootd version.
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PavelDemin - 14-Sep-2012