Working on the PSI CMS Tier-3

The PSI Tier-3 encompasses the following services/machines

• User Interface: This is a fully operational LCG UI. It enables you to
  • login from outside, so it is the standard login node
  • Run local jobs on the Tier-3 using the local batch system (SGE) and CRAB as a front end to it (this still needs testing).
  • Interact with the LCG Grid. Submit jobs, contact storage elements, etc.
  • interact with AFS
• Local batch farm:
  • Allows you to run local jobs on the Tier-3 worker nodes from the User Interface
• Storage Element: This is a fully equipped LCG storage element running a dcache. It allows you to
  • store/read files from local jobs
  • send files to it from your jobs running in the Grid, or have your Grid jobs access files at the PSI SE. This also will give you an extra amount of user space over the space that is available in your Tier-2 associated analysis groups.
• PhEDEx: Our Storage will be coupled to the PhEDEx CMS Data Management System, so we can order data sets to our center from the T2 and the T1s.

Note: As was originally discussed, there is no computing element, so you cannot submit grid jobs to the Tier-3. You need to submit them from the local user interface. This allows us to stay more flexible in respect to configuration, since we want the Tier-3 to adapt best to the users' analysis needs. This is not so easily possible for a Tier-2, where certain configurations must be guaranteed towards the full collaboration. Having only a minimal set of Grid services also cuts down the administration effort significantly.

Login Accounts: All users will require a PSI AFS login account. Instructions on how to get this will be published in due course.

Comments

-- DerekFeichtinger - 21 Aug 2008