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Storage information and the Site Status Board

Storage information and the Site Status Board. Andrea Sciabà. MTF meeting 6/10/201. Outline. SSB storage view Collected information Issues and ambiguities Conclusions. SSB storage view. The goal is to collect storage-related site information in a table The SSB provides historical plots

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Storage information and the Site Status Board

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  1. Storage information and the Site Status Board Andrea Sciabà MTF meeting6/10/201

  2. Outline • SSB storage view • Collected information • Issues and ambiguities • Conclusions

  3. SSB storage view • The goal is to collect storage-related site information in a table • The SSB provides historical plots • Can use colour codes to highlight anomalous values • A previous version existed but it was not maintained and was never used • Useful links: • http://dashb-ssbcern.ch/dashboard/request.py/siteview#currentView=storage • https://twiki.cern.ch/twiki/bin/view/CMS/MonStorageSSB

  4. New storage view layout

  5. PhEDEx information • Custodial: amount of custodial data at the site • Non-custodial: amount of non-custodial data at the site • Incoming: amount of subscribed data not at the site • Total subscribed or resident? • By group? • Caveat: proliferation of columns

  6. Pledges • Taken from SiteDB • Yellow: > 1 quarter old • Red: > 1 year old • Will add those from REBUS • Question: • Which ones are to be trusted more?

  7. BDII information • These GLUE attributes are used and so defined by WLCG: • TotalOnlineSize: the total online space available at a given moment • UsedOnlineSize: the space occupied by available and accessible files that are not candidates for garbage collection • FreeOnlineSize: Total – Used • InstalledOnlineCapacity: used for accounting purposes, the size of the physical space of a SE • Same for Nearline

  8. BDII issues and ambiguities • Information clearly wrong for all T1 sites apart from ASGC • What to report if a SE creates more replicas of some files?

  9. Two conflicting interpretations • “Site” interpretation • Used is the space occupied by files • Free is the space not occupied by files • “User” interpretation • Used is the amount of data stored • Free is the amount of data that could be added • We need both! Naively, one could: • Ask for the BDII to provide the “site” info • Use the PhEDEx agent to calculate the “user” info • Although the “free” space could be tricky: maybe add the “overhëad” as a site-specific parameter?

  10. Pragmatic approach • For the time being, try to make the best possible use of the BDII information • Fix the obvious issues (e.g. RAL declares 2.2 Exabytes of used tape) • Maybe in 90% of cases the numbers are usable for accounting and operations… • Or, ask at least the T1’s to provide their storage usage numbers in a standard format • And stop asking them to update the weekly twiki • Publish the numbers in the SSB

  11. Conclusions • The SSB historical plots could be used to generate storage accounting plots • The SSB is not convenient for too fine-grained information • E.g. disk usage by group • Three main sources of information: • Pledges: REBUS or SiteDB? • PhEDEx agent and namespace dumps for space usage (from CMS point of view) • Site information for physical space usage (either from BDII or from custom sources)

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